As filed with the Securities and Exchange Commission on July 6, 2001

                                                          Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                               -----------------

                                    FORM S-3

                               -----------------

             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                               -----------------

                           ART TECHNOLOGY GROUP, INC.
             (Exact name of registrant as specified in its charter)

                               -----------------

          DELAWARE                                              04-3141918
(State or other jurisdiction of                              (I.R.S. Employer
incorporation or organization)                              Identification No.)

                                 25 FIRST STREET
                         CAMBRIDGE, MASSACHUSETTS 02141
                                 (617) 386-1000
          (Address, including zip code, and telephone number, including
             area code, of registrant's principal executive offices)

                               -----------------

                                   JEET SINGH
                             CHIEF EXECUTIVE OFFICER
                           ART TECHNOLOGY GROUP, INC.
                                 25 FIRST STREET
                         CAMBRIDGE, MASSACHUSETTS 02141
                                 (617) 386-1000
       (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

                               -----------------

                                   Copies to:
           LINDA HANDMAN, ESQ.                   DAVID A. WESTENBERG, ESQ.
            GENERAL COUNSEL                        MARK L. JOHNSON, ESQ.
       ART TECHNOLOGY GROUP, INC.                    HALE AND DORR LLP
             25 First Street                          60 State Street
    Cambridge, Massachusetts 02141               Boston, Massachusetts 02109
      Telephone: (617) 386-1000                   Telephone: (617) 526-6000
       Telecopy: (617) 386-1111                    Telecopy: (617) 526-5000

         APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO PUBLIC: As soon as
practicable after this registration statement is declared effective or, if
later, July 17, 2001.

         If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [ ]

         If any of the securities being registered on this Form are to be
offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, other than securities offered only in connection with
dividend or interest reinvestment plans, check the following box. [X]

         If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [ ] 333-_______.

         If this Form is a post-effective amendment filed pursuant to Rule
462(c) under the Securities Act, check the following box and list the Securities
Act registration statement number of the earlier effective registration
statement for the same offering. [ ] 333-__________.

         If delivery of the prospectus is expected to be made pursuant to Rule
434, please check the following box. [ ]

                               -----------------




                         CALCULATION OF REGISTRATION FEE
-----------------------------------------------------------------------------------------------------------------
                                                                   Proposed        Proposed
                                                                   Maximum         Maximum
                                                     Amount        Offering        Aggregate        Amount of
                                                     to be          Price          Offering       Registration
     Title of Shares to be Registered              Registered     Per Share(1)      Price(1)           Fee
-----------------------------------------------------------------------------------------------------------------
                                                                                      
Common Stock, $.01 par value per share........       18,745         $4.64           $86,977            $22
-----------------------------------------------------------------------------------------------------------------


(1)      Estimated solely for purposes of calculating the registration fee
         pursuant to Rule 457(c) under the Securities Act and based upon the
         average of the high and low prices on the Nasdaq National Market on
         July 3, 2001.

                               -----------------

         The Company hereby amends this Registration Statement on such date or
dates as may be necessary to delay its effective date until the Company shall
file a further amendment which specifically states that this Registration
Statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until the Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a),
shall determine.

================================================================================




THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. THE
SELLING STOCKHOLDERS NAMED IN THIS PROSPECTUS MAY NOT SELL THESE SECURITIES
UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE
COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE
SECURITIES, AND THE SELLING STOCKHOLDERS NAMED IN THIS PROSPECTUS ARE NOT
SOLICITING OFFERS TO BUY THESE SECURITIES, IN ANY JURISDICTION WHERE THE OFFER
OR SALE IS NOT PERMITTED.


                   SUBJECT TO COMPLETION, DATED JULY 6, 2001


PROSPECTUS

                           ART TECHNOLOGY GROUP, INC.

                          18,745 SHARES OF COMMON STOCK

                               -----------------

         This prospectus relates to resales of shares of common stock issued
that we issued to the former stockholders of The Toronto Technology Group Inc.
in connection with our acquisition of that company.

         We will not receive any proceeds from the sale of the shares.

         The selling stockholders identified in this prospectus, or their
pledgees, donees, transferees or other successors-in-interest, may offer the
shares from time to time through public or private transactions at prevailing
market prices, at prices related to prevailing market prices or at privately
negotiated prices.

         Our common stock is traded on the Nasdaq National Market under the
symbol "ARTG." On July 5, 2001, the closing sale price of the common stock on
Nasdaq was $4.28 per share. You are urged to obtain current market quotations
for the common stock.

                               -----------------

         INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. SEE "RISK
FACTORS" BEGINNING ON PAGE 4.

                               -----------------

         NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS
PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

                               -----------------


                 The date of this prospectus is         , 2001.





                                TABLE OF CONTENTS

                                                                       PAGE

            Prospectus Summary.......................................... 3

            The Offering................................................ 3

            Risk Factors................................................ 4

            Special Note Regarding Forward-Looking Information.......... 11

            Use Of Proceeds............................................. 12

            Selling Stockholders........................................ 12

            Plan Of Distribution........................................ 14

            Legal Matters............................................... 15

            Experts..................................................... 15

            Where You Can Find More Information......................... 16

            Incorporation Of Documents By Reference..................... 16


         Unless the context otherwise requires references in this prospectus to
"ATG," "we," "us," and "our" refer to Art Technology Group, Inc. and its
subsidiaries.

         ATG and Dynamo are our registered trademarks and Art Technology Group,
Dynamo Personalization Server, Dynamo Scenario Server and the ATG logo are our
trademarks. J2EE, Java and JavaBeans are trademarks of Sun Microsystems. This
prospectus also contains trademarks and tradenames of other companies.

         We have not authorized anyone to provide you with information different
from that contained or incorporated by reference in this prospectus. The selling
stockholders are offering to sell, and seeking offers to buy, shares of our
common stock only in jurisdictions where offers and sales are permitted.


                                      -2-



                               PROSPECTUS SUMMARY

         THIS SUMMARY DOES NOT CONTAIN ALL OF THE INFORMATION THAT YOU SHOULD
CONSIDER BEFORE INVESTING IN OUR COMMON STOCK. YOU SHOULD READ THE ENTIRE
PROSPECTUS CAREFULLY, INCLUDING THE RISKS OF INVESTING IN OUR COMMON STOCK
DISCUSSED UNDER "RISK FACTORS."

                           ART TECHNOLOGY GROUP, INC.


                                              

OUR BUSINESS:                                    We offer an integrated suite of Internet customer relationship
                                                 management and e-commerce software applications, as well as related
                                                 application development, integration and support services. Our
                                                 solution enables businesses to understand, manage and build online
                                                 customer relationships and to market, sell and support products and
                                                 services over the Internet more effectively. Our Dynamo product
                                                 suite includes an application server that is specifically designed
                                                 to enable and support Web applications, as well as e-commerce and
                                                 Internet customer management applications. An application server is
                                                 a software program that facilitates the development, deployment and
                                                 management of other software programs. Our solution is designed to
                                                 provide businesses with the core application platform and software
                                                 tools required to develop and deploy personalized, reliable,
                                                 large-scale Web sites for conducting  e-commerce.

OUR ADDRESS:                                     Our executive offices are located at 25 First Street, Cambridge,
                                                 Massachusetts 02141.  Our telephone number is (617) 386-1000.  Our
                                                 Internet address is www.atg.com.  The information on our website is
                                                 not incorporated by reference in this prospectus.


                                  THE OFFERING

COMMON STOCK OFFERED:                            The 18,745 shares of common stock offered by this prospectus are
                                                 being sold by the selling stockholders.  The selling stockholders
                                                 are the former stockholders of The Toronto Technology Group Inc.
                                                 who acquired the offered shares in connection with our acquisition
                                                 of The Toronto Technology Group Inc. in July 2000.

USE OF PROCEEDS:                                 We will not receive any proceeds from the sale of shares in this
                                                 offering.

NASDAQ NATIONAL MARKET SYMBOL:                   ARTG



                                      -3-



                                  RISK FACTORS

         INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. YOU
SHOULD CAREFULLY CONSIDER THE RISKS AND UNCERTAINTIES DESCRIBED BELOW BEFORE
PURCHASING OUR COMMON STOCK. THE RISKS AND UNCERTAINTIES DESCRIBED BELOW ARE NOT
THE ONLY ONES FACING OUR COMPANY. ADDITIONAL RISKS AND UNCERTAINTIES MAY ALSO
IMPAIR OUR BUSINESS OPERATIONS. IF ANY OF THE FOLLOWING RISKS ACTUALLY OCCUR,
OUR BUSINESS, FINANCIAL CONDITION OR RESULTS OF OPERATIONS WOULD LIKELY SUFFER.
IN THAT CASE, THE TRADING PRICE OF OUR COMMON STOCK COULD FALL, AND YOU MAY LOSE
ALL OR PART OF THE MONEY YOU PAID TO BUY OUR COMMON STOCK.

RISKS RELATED TO OUR BUSINESS

WE EXPECT OUR LOSSES TO CONTINUE AND WE DO NOT BELIEVE WE WILL BE ABLE TO
SUSTAIN OUR CURRENT REVENUE GROWTH RATE, AND WE CANNOT BE CERTAIN THAT WE WILL
BE ABLE TO ATTAIN, SUSTAIN OR INCREASE PROFITABILITY ON A QUARTERLY OR ANNUAL
BASIS.

         We incurred a loss in the first quarter of 2001, and the second, third
and fourth quarters of 2000 were our first profitable quarters since inception.
We have incurred substantial costs to develop and enhance our technology and
products, to recruit and train a marketing and sales group, and to establish an
administrative organization. As of March 31, 2001, we had an accumulated deficit
of $27.3 million. We anticipate that our operating expenses will increase as we
continue to develop our technology, increase our sales and marketing activities,
create and expand our distribution channels, expand our services capabilities
and improve our operational and financial systems. Although our revenues have
grown significantly, they have grown from a relatively small base and, as a
result, we do not believe that we will be able to sustain the growth rates we
have achieved in recent quarters. In addition, we believe the current United
States economic downturn will have an adverse effect on demand for our products
and services, and therefore adversely affect our revenues as well. Because we
have a limited operating history, particularly as a company that sells software
products, we have difficulty predicting our future operating results and we
cannot be certain that our revenues will grow at a rate that will allow us to
achieve profitability. In addition, we cannot be certain that if we do achieve
profitability, that we will be able to sustain or increase profitability on a
quarterly or annual basis.

WE EXPECT OUR OPERATING RESULTS TO FLUCTUATE AND THE PRICE OF OUR COMMON STOCK
COULD FALL IF QUARTERLY RESULTS ARE LOWER THAN THE EXPECTATIONS OF SECURITIES
ANALYSTS.

         Our revenues and operating results are likely to vary significantly
from quarter to quarter. If our quarterly results fall below the expectations of
securities analysts, the price of our common stock could fall. A number of
factors are likely to cause variations in our operating results, including:

         o        demand for our products and services;

         o        the timing of sales of our products and services;

         o        the timing of customer orders and product implementations;

         o        unexpected delays in introducing new products and services;

         o        increased expenses, whether related to sales and marketing,
                  product development or administration;

         o        changes in the rapidly evolving market for Internet customer
                  relationship management solutions;

         o        the mix of revenues derived from products and services;

         o        cost overruns related to fixed price services projects;

         o        the mix of domestic and international sales; and

         o        costs related to possible acquisitions of technologies or
                  businesses.

         Accordingly, we believe that quarter-to-quarter comparisons of our
operating results are not necessarily meaningful. The results of one or a series
of quarters should not be relied upon as an indication of our future
performance.


                                      -4-



         We plan to increase our operating expenses to expand our sales and
marketing operations, develop new distribution channels, fund greater levels of
research and development, broaden professional services and support and improve
our operational and financial systems. If our revenues do not increase as
quickly as these expenses, our operating results may suffer and our stock price
may decline.

OUR LENGTHY SALES CYCLE MAKES IT DIFFICULT TO PREDICT OUR QUARTERLY RESULTS.

         Our long sales cycle, which can range from several weeks to several
months or more, makes it difficult to predict the quarter in which sales may
occur. We have a long sales cycle because we generally need to educate potential
customers regarding the use and benefits of our products and services. Our sales
cycle varies depending on the size and type of customer contemplating a purchase
and whether we have conducted business with a potential customer in the past. In
addition, we believe the current economic downturn in the United States has
increased the average length of our sales cycle as customers have deferred
implementing new e-commerce solutions. We may incur significant sales and
marketing expenses in anticipation of licensing our products, and if we do not
achieve the level of revenues we expected, our operating results will suffer and
our stock price may decline. These potential customers frequently need to obtain
approvals from multiple decision makers prior to making purchase decisions.
Delays in sales could cause significant variability in our revenues and
operating results for any particular period.

THE MARKET FOR INTERNET CUSTOMER RELATIONSHIP MANAGEMENT SOLUTIONS IS NEW AND
RAPIDLY EVOLVING AND WE CANNOT BE CERTAIN THAT A VIABLE MARKET FOR OUR PRODUCTS
WILL EMERGE OR BE SUBSTANTIAL.

         The market for Internet customer relationship management solutions is
new and rapidly evolving. We expect that we will continue to need intensive
marketing and sales efforts to educate prospective customers and partners about
the uses and benefits of our products and services. Accordingly, we cannot be
certain that a viable market for our products is sustainable. Organizations that
have already invested substantial resources in other methods of conducting
business may be reluctant or slow to adopt a new approach that may replace,
limit or compete with their existing systems.

THE MARKET FOR INTERNET CUSTOMER RELATIONSHIP MANAGEMENT SOLUTIONS IS INTENSELY
COMPETITIVE AND WE EXPECT COMPETITION TO INTENSIFY IN THE FUTURE.

         The market for Internet customer relationship management solutions is
intensely competitive and we expect competition to intensify in the future as
revenues generated from Internet commerce increase. This level of competition
could reduce our revenues and result in increased losses or reduced profits. Our
primary competition currently comes from in-house development efforts by
potential customers or partners, as well as from other vendors of Web-based
application software. We currently compete with Internet application software
vendors such as Blue Martini, BroadVision and Vignette. We also compete with
platform application server products and vendors such as BEA Systems, IBM's
Websphere products, Microsoft, Netscape and the Netscape/Sun Microsystems
Alliance, among others. Many of our competitors have longer operating histories
and significantly greater financial, technical, marketing and other resources
than we do, and may be able to respond more quickly to new or changing
opportunities, technologies and customer requirements. Also, many current and
potential competitors have greater name recognition and more extensive customer
bases that they can leverage to gain market share. These competitors may be able
to undertake more extensive promotional activities, adopt more aggressive
pricing policies and offer more attractive terms to purchasers than we can.
Moreover, our current and potential competitors, such as Microsoft and the
Netscape/Sun Microsystems Alliance, may bundle their products in a manner that
may discourage users from purchasing our products. In addition, current and
potential competitors have established or may establish cooperative
relationships among themselves or with third parties to enhance their products
and expand their markets. Accordingly, new competitors or alliances among
competitors may emerge and rapidly acquire significant market share.

WE DEPEND ON OUR RELATIONSHIPS WITH SYSTEMS INTEGRATORS.

         Since our potential customers often rely on third-party systems
integrators to develop, deploy and manage Web sites for conducting commerce on
the Internet, we cultivate relationships with systems integrators in order to
encourage them to support our products. If we do not adequately train a
sufficient number of systems integrators or


                                      -5-



if systems integrators were to devote their efforts to integrating or co-selling
different products, our revenues could be reduced and our operating results
could be harmed.

WE WILL NEED TO IMPLEMENT AND IMPROVE OUR OPERATIONAL SYSTEMS AND HIRE
ADDITIONAL SERVICE PROFESSIONALS ON A TIMELY BASIS IN ORDER TO MANAGE GROWTH.

         We have expanded our operations rapidly in recent years. We intend to
continue to expand in the foreseeable future to pursue existing and potential
market opportunities and to support our growing customer base. Rapid growth
places a significant demand on our management and operational resources. In
order to manage growth effectively, we must implement and improve our
operational systems, procedures and controls on a timely basis. We plan in
particular to expand our professional services capabilities to support increased
product license sales. However, we cannot be certain that we will be able to
attract a sufficient number of highly qualified service personnel. In addition,
new service personnel will require training and it will take time for them to
become productive. If we fail to improve operational systems or to expand our
professional service capabilities in a timely manner, we could experience
customer dissatisfaction, cost inefficiencies and lost revenue opportunities,
which could harm our operating results.

COMPETITION WITH OUR RESELLER PARTNERS COULD LIMIT OUR SALES OPPORTUNITIES AND
JEOPARDIZE THESE RELATIONSHIPS.

         We sell products through resellers and original equipment
manufacturers. In some instances, we target our direct selling efforts toward
markets that are also served by some of these partners. This competition may
limit our ability to sell our products and services directly in these markets
and may jeopardize, or result in the termination of, these relationships.

OUR BUSINESS MAY BE HARMED IF WE LOSE THE SERVICES OF EITHER JEET SINGH OR
JOSEPH CHUNG, OUR CO-FOUNDERS, OR IF WE ARE UNABLE TO ATTRACT AND RETAIN OTHER
KEY PERSONNEL.

         Our success depends largely on the skills, experience and performance
of some key members of our management, particularly our co-founders Jeet Singh
and Joseph Chung. If we lose one or more of our key employees, our business
could be harmed. We have purchased, and are the beneficiaries of, insurance
policies on the lives of Mr. Singh and Mr. Chung, each in the amount of
$1,000,000. Proceeds under this insurance may not cover our losses. In addition,
our future success will depend in large part on our ability to continue
attracting and retaining highly skilled personnel. Like other software
companies, we face intense competition for qualified personnel. We may not be
successful in attracting, assimilating and retaining qualified personnel in the
future.

WE NEED TO EXPAND OUR SALES AND DISTRIBUTION CAPABILITIES IN ORDER TO INCREASE
MARKET AWARENESS OF OUR PRODUCTS AND INCREASE OUR REVENUES.

         We must expand our direct and indirect sales operations to increase
market awareness of our products and generate increased revenues. We may not be
successful in these efforts. We have recently expanded our direct sales force
and plan to hire additional sales personnel. Our products and services require a
sophisticated sales effort targeted at the senior management of our prospective
customers. Newly-hired employees will require training and it will take time for
them to achieve full productivity. We may be unable to hire enough qualified
individuals in the future, and newly hired employees may not achieve necessary
levels of productivity.

WE COULD INCUR SUBSTANTIAL COSTS DEFENDING OUR INTELLECTUAL PROPERTY FROM
INFRINGEMENT OR A CLAIM OF INFRINGEMENT.

         Our Innovation Solutions services often involve the development of
custom software applications for specific customers. In some cases, customers
retain ownership or impose restrictions on our ability to use the technologies
developed from these projects. Issues relating to the ownership of software can
be complicated, and disputes could arise that affect our ability to resell or
reuse applications we develop for customers.

         We seek to protect the source code for our proprietary software both as
a trade secret and as a copyrighted work. However, because we make the source
code available to some customers, third parties may be more likely to


                                      -6-



misappropriate it. Our policy is to enter into confidentiality agreements with
our employees, consultants, vendors and customers and to control access to our
software, documentation and other proprietary information. Despite these
precautions, it may be possible for someone to copy our software or other
proprietary information without authorization or to develop similar software
independently.

         In recent years, there has been significant litigation in the United
States involving patents and other intellectual property rights. We could incur
substantial costs to prosecute or defend any intellectual property litigation.
If we sue to enforce our rights, the litigation would be expensive, would divert
management resources and may not prevent the other parties from using our
intellectual property without permission. In February 2000, we settled a lawsuit
filed by BroadVision, which alleged that we were infringing on a patent for a
method of conducting e-commerce. As part of the settlement, we agreed to pay
BroadVision a total of $15.0 million in license fees over a three-year period,
of which $11.8 million had been paid as of March 31, 2001.

         In addition, we have agreed to indemnify customers against claims that
our products infringe the intellectual property rights of third parties. The
results of any intellectual property litigation to which we might become a party
may force us to do one or more of the following:

         o        cease selling or using products or services that incorporate
                  the challenged intellectual property;

         o        obtain a license, which may not be available on reasonable
                  terms, to sell or use the relevant technology; or

         o        redesign those products or services to avoid infringement.

IF WE FAIL TO ADAPT TO RAPID CHANGES IN THE INTERNET CUSTOMER RELATIONSHIP
MANAGEMENT SOFTWARE MARKET, OUR EXISTING PRODUCTS COULD BECOME OBSOLETE.

         The market for our products is marked by rapid technological change,
frequent new product introductions and Internet-related technology enhancements,
uncertain product life cycles, changes in customer demands and evolving industry
standards. We may not be able to develop and market new products or product
enhancements that comply with present or emerging Internet technology standards.
New products based on new technologies or new industry standards could render
our existing products obsolete and unmarketable. To succeed, we will need to
enhance our current products and develop new products on a timely basis to keep
pace with developments related to Internet technology and to satisfy the
increasingly sophisticated requirements of customers. E-commerce technology is
complex and new products and product enhancements can require long development
and testing periods. Any delays in developing and releasing enhanced or new
products could cause us to lose revenue opportunities and customers.

OUR BUSINESS MAY SUFFER IF WE FAIL TO ADDRESS THE CHALLENGES ASSOCIATED WITH
INTERNATIONAL OPERATIONS.

         We have recently begun to invest significant financial and managerial
resources to expand our sales and marketing operations in international markets.
We currently maintain offices in Australia, Canada, England, France, Germany,
Hong Kong, Japan, the Netherlands, Singapore and Sweden. We derived 33% of our
total revenues from customers outside the United States for the three months
ended March 31, 2001. We anticipate that revenues from customers outside the
United States will account for an increased portion of our total revenues for
the foreseeable future. To date, however, we have limited experience in
international operations and may not be able to compete successfully in
international markets. Our operations outside North America are subject to
additional risks, including:

         o        unexpected changes in regulatory requirements, exchange rates,
                  tariffs and other barriers;

         o        longer payment cycles and problems in collecting accounts
                  receivable;

         o        political and economic instability;

         o        difficulties in managing system integrators and technology
                  partners;

         o        difficulties in staffing and managing foreign subsidiary
                  operations;

         o        differing technology standards;


                                      -7-



         o        difficulties and delays in translating products and product
                  documentation into foreign languages;

         o        reduced protection for intellectual property rights in some of
                  the countries in which we operate or plan to operate;

         o        problems associated with the conversion of various European
                  currencies into a single currency, the Euro; and

         o        potentially adverse tax consequences.

         The impact of future exchange rate fluctuations on our operating
results cannot be accurately predicted. We may increase the extent to which we
denominate arrangements with international customers in the currencies of the
countries in which the software or services are provided. From time to time we
may engage in hedges of a significant portion of contracts denominated in
foreign currencies. Any hedging policies implemented by us may not be
successful, and the cost of these hedging techniques may have a significant
negative impact on our operating results.

WE RELY ON JAVA AS THE PROGRAMMING LANGUAGE IN WHICH WE DEVELOP OUR PRODUCTS AND
OUR BUSINESS COULD BE HARMED IF JAVA LOSES MARKET ACCEPTANCE OR IF WE ARE NOT
ABLE TO CONTINUE USING JAVA OR JAVA RELATED TECHNOLOGIES.

         We write our software in the Java computer programming language
developed by Sun Microsystems. While a number of companies have introduced Web
applications based on Java, Java could fall out of favor, and support by Sun
Microsystems or other companies could decline. Moreover, our new Dynamo 5
e-Business Platform is designed to support Sun's Java 2 Platform, Enterprise
Edition, or J2EE, standards for developing modular Java programs that can be
accessed over a network. We have licensed the J2EE brand and certification tests
from Sun. There can be no assurance that these standards will be widely adopted,
that we can continue to support J2EE standards established by Sun from time to
time or that the J2EE brand will continue to be made available to us on
commercially reasonable terms. If Java or J2EE support decreased or we could not
continue to use Java or related Java technologies or to support J2EE, we might
have to rewrite the source code for our entire product line to enable our
products to run on other computer platforms. Also, changes to Java or J2EE
standards or the loss of our license to the J2EE brand could require us to
change our products and adversely affect the perception of our products by our
customers. If we were unable to develop or implement appropriate modifications
to our products on a timely basis, we could lose revenue opportunities and our
business could be harmed.

OUR SOFTWARE PRODUCTS MAY CONTAIN ERRORS OR DEFECTS THAT COULD RESULT IN LOST
REVENUES, DELAYED OR LIMITED MARKET ACCEPTANCE, OR PRODUCT LIABILITY CLAIMS WITH
SUBSTANTIAL LITIGATION COSTS.

         Complex software products such as ours often contain errors or defects,
particularly when first introduced or when new versions or enhancements are
released. We began shipping our new application suite, Dynamo 5 e-business
Platform, in September 2000. Despite internal testing and testing by customers,
our current and future products may contain serious defects. Serious defects or
errors could result in lost revenues or a delay in market acceptance.

         Since our customers use our products for critical business applications
such as e-commerce, errors, defects or other performance problems could result
in damage to our customers. They could seek significant compensation from us for
the losses they suffer. Although our license agreements typically contain
provisions designed to limit our exposure to product liability claims, existing
or future laws or unfavorable judicial decisions could negate these limitations.
Even if not successful, a product liability claim brought against us would
likely be time-consuming and costly.

IF WE ACQUIRE OTHER COMPANIES OR BUSINESSES, WE WILL BE SUBJECT TO RISKS THAT
COULD HURT OUR BUSINESS.

         We acquired Petronio Technology Group in May 2000 for consideration of
$1.2 million and the Toronto Technology Group in July 2000 for consideration of
$12.0 million. In the future, we may pursue additional acquisitions to obtain
complementary businesses, products, services or technologies. An acquisition may
not produce the revenues, earnings or business synergies that we anticipated,
and an acquired business, product, service


                                      -8-



or technology might not perform as we expected. If we pursue an acquisition, our
management could spend a significant amount of time and effort in identifying
and completing the acquisition. If we complete an acquisition, we may encounter
significant difficulties and incur substantial expense in integrating the
operations and personnel of the acquired company into our operation while
preserving the goodwill of the acquired company. In particular, we may lose the
services of key employees of the acquired company and we may make changes in
management that impair the acquired company's relationships with employees and
customers.

         Any of these outcomes could prevent us from realizing the anticipated
benefits of our acquisitions. To pay for an acquisition, we might use stock or
cash. Alternatively, we might borrow money from a bank or other lender. If we
use our stock, our stockholders would experience dilution of their ownership
interests. If we use cash or debt financing, our financial liquidity would be
reduced. Finally, if we are unable to account for our acquisitions under the
"pooling-of-interests" method of accounting, which may be eliminated, we may be
required to capitalize a significant amount of intangibles, including goodwill,
which may lead to significant amortization charges. In addition, we may incur
significant, one-time write-offs and amortization charges. These amortization
charges and write-offs could decrease our future earnings or increase our future
losses.

RISKS RELATED TO THE INTERNET INDUSTRY

OUR PERFORMANCE WILL DEPEND ON THE GROWTH OF E-COMMERCE.

         Our success will depend heavily on the acceptance and wide use of the
Internet for e-commerce. The current United States economic downturn will reduce
demand for our products if customers and potential customers delay or cancel the
implementation of customer relationship management solutions. Consumers and
businesses may reject the Internet as a viable commercial medium for a number of
reasons, including potentially inadequate network infrastructure, slow
development of enabling technologies, insufficient commercial support or privacy
concerns. The Internet infrastructure may not be able to support the demands
placed on it by increased usage. In addition, delays in the development or
adoption of new standards and protocols required to handle increased levels of
Internet activity, or increased government regulation could cause the Internet
to lose its viability as a commercial medium. Even if the required
infrastructure, standards, protocols and complementary products, services or
facilities are developed, we may incur substantial expenses adapting our
solutions to changing or emerging technologies.

REGULATIONS COULD BE ENACTED THAT EITHER DIRECTLY RESTRICT OUR BUSINESS OR
INDIRECTLY IMPACT OUR BUSINESS BY LIMITING THE GROWTH OF E-COMMERCE.

         As e-commerce evolves, federal, state and foreign agencies could adopt
regulations covering issues such as user privacy, content and taxation of
products and services. If enacted, government regulations could limit the market
for our products and services or could impose burdensome requirements that
render our business unprofitable. Although many regulations might not apply to
our business directly, we expect that laws regulating the solicitation,
collection or processing of personal and consumer information could indirectly
affect our business. The Telecommunications Act of 1996 prohibits certain types
of information and content from being transmitted over the Internet. The
prohibition's scope and the liability associated with a violation are currently
unsettled. In addition, although substantial portions of the Communications
Decency Act were held to be unconstitutional, we cannot be certain that similar
legislation will not be enacted and upheld in the future. It is possible that
legislation could expose companies involved in e-commerce to liability, which
could limit the growth of e-commerce generally. Legislation like the
Telecommunications Act and the Communications Decency Act could dampen the
growth in Web usage and decrease its acceptance as a medium of communications
and commerce.

THE INTERNET IS GENERATING PRIVACY CONCERNS THAT COULD RESULT IN LEGISLATION OR
MARKET PERCEPTIONS THAT COULD HARM OUR BUSINESS OR RESULT IN REDUCED SALES OF
OUR PRODUCTS, OR BOTH.

         Businesses use our Dynamo Personalization Server product to develop and
maintain profiles to tailor the content to be provided to Web site visitors.
When a visitor first arrives at a Web site, our software creates a profile for
that visitor. If the visitor registers or logs in, the visitor's identity is
added to the profile, preserving any profile information that was gathered up to
that point. Dynamo Personalization Server tracks both explicit user profile data
supplied by the user as well as implicit profile attributes derived from the
user's behavior on the Web site. Privacy concerns may cause visitors to resist
providing the personal data or avoid Web sites tracking the Web behavioral


                                      -9-



information necessary to support this profiling capability. More importantly,
even the perception of security and privacy concerns, whether or not valid, may
indirectly inhibit market acceptance of our products. In addition, legislative
or regulatory requirements may heighten these concerns if businesses must notify
Web site users that the data captured after visiting Web sites may be used to
direct product promotion and advertising to that user. Other countries and
political entities, such as the European Economic Community, have adopted such
legislation or regulatory requirements. The United States may adopt similar
legislation or regulatory requirements. If privacy legislation is enacted or
consumer privacy concerns are not adequately addressed, our business, financial
condition and operating results could be harmed.

         Our products use "cookies" to track demographic information and user
preferences. A "cookie" is information keyed to a specific user that is stored
on a computer's hard drive, typically without the user's knowledge. Cookies are
generally removable by the user, although removal could affect the content
available on a particular site. Germany has imposed laws limiting the use of
cookies, and a number of Internet commentators and governmental bodies in the
United States and other countries have urged passage of laws limiting or
abolishing the use of cookies. If such laws are passed or if users begin to
delete or refuse cookies as a common practice, demand for our personalization
products could be reduced.

PROJECTIONS INCORPORATED IN THIS PROSPECTUS RELATING TO THE GROWTH OF E-COMMERCE
AND THE INTERNET ARE BASED ON ASSUMPTIONS THAT COULD TURN OUT TO BE INCORRECT
AND ACTUAL RESULTS COULD BE MATERIALLY DIFFERENT FROM THE PROJECTIONS.

         The documents incorporated by reference in this prospectus contain
various data and projections related to revenues generated by electronic
commerce and the size of the worldwide Internet commerce application software
market. These data and projections are inherently imprecise, and investors are
cautioned not to place undue reliance on them. These data and projections have
been included in studies prepared by International Data Corporation, an
independent market research firm, and the projections are based on surveys,
financial reports and models used by IDC to measure license revenues and
associated maintenance fees derived from sales to e-commerce sites. These
projections include assumptions regarding business and home use of the Internet,
including assumptions as to growth in the percentage of Web users making online
purchases, increases in the amount of time people spend using the Web, changing
attitudes toward Web usage and purchasing, levels of business saturation for Web
use and increases in the level of software spending by businesses, as well as
various assumptions regarding the rate of growth of Web use in countries outside
the United States. Actual results or circumstances may be materially different
from the projections.

RISKS RELATED TO THE SECURITIES MARKET

OUR STOCK PRICE MAY BE VOLATILE.

         The market price of our common stock has fluctuated in the past and is
likely to continue to be highly volatile. For example, the market price of our
common stock has ranged from $4.05 per share to $126.88 per share since our
initial public offering in July 1999. Fluctuations in market price and volume
are particularly common among securities of Internet and software companies. The
market price of our common stock may fluctuate significantly in response to the
following factors, some of which are beyond our control:

         o        variations in our quarterly operating results;

         o        changes in market valuations of Internet and software
                  companies;

         o        our announcements of significant contracts, acquisitions,
                  strategic partnerships, joint ventures or capital commitments;

         o        our failure to complete significant sales;

         o        additions or departures of our key personnel;

         o        future sales of our common stock; or

         o        changes in financial estimates by securities analysts.


                                      -10-



WE MAY INCUR SIGNIFICANT COSTS FROM CLASS ACTION LITIGATION.

         In the past, securities class action litigation has often been brought
against a company following periods of volatility in the market price of its
stock. We may be the target of similar litigation in the future. Securities
litigation could result in substantial costs and divert management's attention
and resources.

OUR EXISTING STOCKHOLDERS WILL BE ABLE TO INFLUENCE ALL MATTERS REQUIRING
STOCKHOLDER APPROVAL AND COULD DELAY OR PREVENT SOMEONE FROM ACQUIRING OR
MERGING WITH US ON TERMS FAVORED BY A MAJORITY OF OUR INDEPENDENT STOCKHOLDERS.

         Our executive officers and directors beneficially owned approximately
20% of our common stock as of April 30, 2001. As a result, these stockholders
may be able to influence matters requiring stockholder approval, including the
election of directors and approval of significant corporate transactions. This
could delay or prevent someone from acquiring or merging with us.

ANTI-TAKEOVER PROVISIONS IN OUR CHARTER DOCUMENTS AND DELAWARE LAW COULD PREVENT
OR DELAY A CHANGE IN CONTROL OF OUR COMPANY.

         Certain provisions of our certificate of incorporation and by-laws may
discourage, delay or prevent a merger or acquisition that a stockholder may
consider favorable, which could reduce the market price of our common stock.
These provisions include:

         o        authorizing the issuance of "blank check" preferred stock;

         o        providing for a classified board of directors with staggered,
                  three-year terms;

         o        providing that directors may only be removed for cause by a
                  two-thirds vote of stockholders;

         o        limiting the persons who may call special meetings of
                  stockholders prohibiting stockholder action by written
                  consent; and

         o        establishing advance notice requirements for nominations for
                  election to the board of directors or for proposing matters
                  that can be acted on by stockholders at stockholder meetings.

         Delaware law may also discourage, delay or prevent someone from
acquiring or merging with us.

               SPECIAL NOTE REGARDING FORWARD-LOOKING INFORMATION

         This prospectus includes and incorporates forward-looking statements
within the meaning of Section 27A of the Securities Act of 1933 and Section 21E
of the Securities Exchange Act of 1934. All statements, other than statements of
historical facts, included or incorporated in this prospectus regarding our
strategy, future operations, financial position, future revenues, projected
costs, prospects, plans and objectives of management are forward-looking
statements. The words "anticipates," "believes," "estimates," "expects,"
"intends," "may," "plans," "projects," "will," "would" and similar expressions
are intended to identify forward-looking statements, although not all
forward-looking statements contain these identifying words. We cannot guarantee
that we actually will achieve the plans, intentions or expectations disclosed in
our forward-looking statements and you should not place undue reliance on our
forward-looking statements. Actual results or events could differ materially
from the plans, intentions and expectations disclosed in the forward-looking
statements we make. We have included important factors in the cautionary
statements included or incorporated in this prospectus, particularly under the
heading "Risk Factors", that we believe could cause actual results or events to
differ materially from the forward-looking statements that we make. Our
forward-looking statements do not reflect the potential impact of any future
acquisitions, mergers, dispositions, joint ventures or investments we may make.
We do not assume any obligation to update any forward-looking statements.


                                      -11-



                                 USE OF PROCEEDS

         We will not receive any proceeds from the sale of shares by the selling
stockholders.

         The selling stockholders will pay any underwriting discounts and
commissions and expenses incurred by the selling stockholders for brokerage,
accounting, tax or legal services or any other expenses incurred by the selling
stockholders in disposing of the shares. We will bear all other costs, fees and
expenses incurred in effecting the registration of the shares covered by this
prospectus, including all registration and filing fees and expenses of our
counsel and accountants.

                              SELLING STOCKHOLDERS

         We are obligated to issue the shares of common stock covered by this
prospectus as the result of agreements entered into in connection with our
acquisition of The Toronto Technology Group Inc. in July 2000. The following
table sets forth, to our knowledge, information about the selling stockholders
as of June 29, 2001.

         Beneficial ownership is determined in accordance with the rules of the
SEC, and includes voting or investment power with respect to shares. Unless
otherwise indicated below, to our knowledge, all persons named in the table have
sole voting and investment power with respect to their shares of common stock,
except to the extent authority is shared by spouses under applicable law.




                                    SHARES OF COMMON STOCK        NUMBER OF SHARES   SHARES OF COMMON STOCK TO BE
                                  BENEFICIALLY OWNED PRIOR TO     OF COMMON STOCK      BENEFICIALLY OWNED AFTER
 NAME OF SELLING STOCKHOLDER               OFFERING                BEING OFFERED               OFFERING
-----------------------------     ---------------------------     ----------------   ----------------------------
                                    NUMBER         PERCENTAGE                           NUMBER        PERCENTAGE
                                    ------         ----------                           ------        ----------
                                                                                       

Henry Edwin Van Beilen               23,073             *               5,881             17,192          *

Glenn James                           5,263             *               1,102              4,161          *

Gerard W. H. van Leeuwen             22,981             *               5,881             17,100          *

Timothy F. Moody                     23,091             *               5,881             17,210          *


--------------------------
* Less than one percent.

         The shares of common stock owned by the selling stockholders but not
offered by this prospectus consist of exchangeable shares of Art Technology
Group (Canada) Inc. that can, at the election of the selling stockholders, be
redeemed for shares of our common stock. As of July 17, 2001 we will have a
repurchase option for a total of 37,492 exchangeable shares of Art Technology
Group (Canada) Inc. listed as being held by the selling stockholders. The
selling stockholders are not entitled to transfer 18,746 exchangeable shares of
Art Technology Group (Canada) Inc., or the shares of our common stock for which
those exchangeable shares can be redeemed, until July 17, 2002, and are not
entitled to transfer an additional 18,746 exchangeable shares of Art Technology
Group (Canada) Inc., or the shares of our common stock for which those
exchangeable shares can be redeemed, until July 17, 2003.

         The following table sets forth, to our knowledge, the composition of
each selling stockholder's common stock beneficially owned prior to the
offering, as shown in the table above, as of June 29, 2001.




                                               EXCHANGEABLE SHARES     SHARES OF COMMON STOCK
                             EXCHANGEABLE        REDEEMABLE ON       ISSUABLE UPON EXERCISE OF
     NAME OF SELLING       SHARES REDEEMABLE    JULY 17, 2002 OR     OPTIONS EXERCISABLE WITHIN      SHARES OF
       STOCKHOLDER         ON JULY 17, 2001      JULY 17, 2003        60 DAYS OF JUNE 29, 2001      COMMON STOCK
-----------------------    -----------------   -------------------   --------------------------  ------------------
                                                                                        

Henry Edwin Van Beilen            5,881              11,762                   5,370                      60

Glenn James                       1,102               2,206                   1,955                       0

Gerard W. H. van Leeuwen          5,881              11,762                   5,338                       0

Timothy F. Moody                  5,881              11,762                   5,448                       0



                                      -12-



         We do not know when or in what amounts a selling stockholder may offer
shares for sale. The selling stockholders may not sell any or all of the shares
offered by this prospectus. Because the selling stockholders may offer all or
some of the shares pursuant to this offering, and because there are currently no
agreements, arrangements or understandings with respect to the sale of any of
the shares, we cannot estimate the number of the shares that will be held by the
selling stockholders after completion of the offering. For purposes of the above
table, we have assumed that, after completion of the offering, none of the
shares covered by this prospectus will be held by the selling stockholders.

         Each of the Selling Stockholders has been an employee or director of
The Toronto Technology Group Inc. or Art Technology Group (Canada) Inc. for the
past three years. Other than those positions, none of the selling stockholders
has held any position or office with, or has otherwise had a material
relationship with, us or any of our subsidiaries within the past three years.


                                      -13-



                              PLAN OF DISTRIBUTION

         The shares covered by this prospectus may be offered and sold from time
to time by the selling stockholders. The term "selling stockholders" includes
donees, pledgees, transferees or other successors-in-interest selling shares
received after the date of this prospectus from a selling stockholder as a gift,
pledge, partnership distribution or other non-sale related transfer. The selling
stockholders will act independently of us in making decisions with respect to
the timing, manner and size of each sale. Such sales may be made on one or more
exchanges or in the over-the-counter market or otherwise, at prices and under
terms then prevailing or at prices related to the then current market price or
in negotiated transactions. The selling stockholders may sell their shares by
one or more of, or a combination of, the following methods:

         o        purchases by a broker-dealer as principal and resale by such
                  broker-dealer for its own account pursuant to this prospectus;

         o        ordinary brokerage transactions and transactions in which the
                  broker solicits purchasers;

         o        block trades in which the broker-dealer so engaged will
                  attempt to sell the shares as agent but may position and
                  resell a portion of the block as principal to facilitate the
                  transaction;

         o        an over-the-counter distribution in accordance with the rules
                  of the Nasdaq National Market;

         o        in privately negotiated transactions; and

         o        in options transactions.

         In addition, any shares that qualify for sale pursuant to Rule 144 may
be sold under Rule 144 rather than pursuant to this prospectus.

         To the extent required, this prospectus may be amended or supplemented
from time to time to describe a specific plan of distribution. In connection
with distributions of the shares or otherwise, the selling stockholders may
enter into hedging transactions with broker-dealers or other financial
institutions. In connection with such transactions, broker-dealers or other
financial institutions may engage in short sales of the common stock in the
course of hedging the positions they assume with selling stockholders. The
selling stockholders may also sell the common stock short and redeliver the
shares to close out such short positions. The selling stockholders may also
enter into option or other transactions with broker-dealers or other financial
institutions which require the delivery to such broker-dealer or other financial
institution of shares offered by this prospectus, which shares such
broker-dealer or other financial institution may resell pursuant to this
prospectus (as supplemented or amended to reflect such transaction). The selling
stockholders may also pledge shares to a broker-dealer or other financial
institution, and, upon a default, such broker-dealer or other financial
institution, may effect sales of the pledged shares pursuant to this prospectus
(as supplemented or amended to reflect such transaction).

         In effecting sales, broker-dealers or agents engaged by the selling
stockholders may arrange for other broker-dealers to participate. Broker-dealers
or agents may receive commissions, discounts or concessions from the selling
stockholders in amounts to be negotiated immediately prior to the sale.

         In offering the shares covered by this prospectus, the selling
stockholders and any broker-dealers who execute sales for the selling
stockholders may be deemed to be "underwriters" within the meaning of the
Securities Act in connection with such sales. Any profits realized by the
selling stockholders and the compensation of any broker-dealer may be deemed to
be underwriting discounts and commissions.

         In order to comply with the securities laws of certain states, if
applicable, the shares must be sold in such jurisdictions only through
registered or licensed brokers or dealers. In addition, in certain states the
shares may not be sold unless they have been registered or qualified for sale in
the applicable state or an exemption from the registration or qualification
requirement is available and is complied with.

         We have advised the selling stockholders that the anti-manipulation
rules of Regulation M under the Exchange Act may apply to sales of shares in the
market and to the activities of the selling stockholders and their affiliates.
In addition, we will make copies of this prospectus available to the selling
stockholders for the purpose of satisfying the prospectus delivery requirements
of the Securities Act. The selling stockholders may indemnify any


                                      -14-



broker-dealer that participates in transactions involving the sale of the shares
against certain liabilities, including liabilities arising under the Securities
Act.

         At the time a particular offer of shares is made, if required, a
prospectus supplement will be distributed that will set forth the number of
shares being offered and the terms of the offering, including the name of any
underwriter, dealer or agent, the purchase price paid by any underwriter, any
discount, commission and other item constituting compensation, any discount,
commission or concession allowed or reallowed or paid to any dealer, and the
proposed selling price to the public.

         We have agreed to indemnify the selling stockholders against certain
liabilities, including certain liabilities under the Securities Act.

         We have agreed with the selling stockholders to keep the Registration
Statement of which this prospectus constitutes a part effective until the
earlier of (i) such time as all of the shares covered by this prospectus have
been disposed of pursuant to and in accordance with the Registration Statement
or (ii) ten days from the effective date of the Registration Statement, subject
to extension in specified circumstances. We may elect, in our discretion, to
keep the Registration Statement effective beyond the ten-day period if some of
the requested shares have not been sold by that time.

                                  LEGAL MATTERS

         The validity of the shares offered by this prospectus has been passed
upon by Hale and Dorr LLP.

                                     EXPERTS

         The consolidated balance sheets of Art Technology Group, Inc. as of
December 31, 1999 and 2000 and the related consolidated statements of
operations, stockholders' equity (deficit) and cash flows for each of the years
in the three year period ended December 31, 2000, incorporated by reference into
this Registration Statement have been audited by Arthur Andersen LLP,
independent public accountants, as indicated in their reports with respect
thereto, and are included herein in reliance upon the authority of said firm as
experts in giving said reports.


                                      -15-



                       WHERE YOU CAN FIND MORE INFORMATION

         We file reports, proxy statements and other documents with the SEC. You
may read and copy any document we file at the SEC's public reference room at
Judiciary Plaza Building, 450 Fifth Street, N.W., Room 1024, Washington, D.C.
20549. You should call 1-800-SEC-0330 for more information on the public
reference room. Our SEC filings are also available to you on the SEC's website
at http://www.sec.gov.

         This prospectus is part of a registration statement that we filed with
the SEC. The registration statement contains more information than this
prospectus regarding us and our common stock, including certain exhibits and
schedules. You can obtain a copy of the registration statement from the SEC at
the address listed above or from the SEC's website.

                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

         The SEC requires us to "incorporate" into this prospectus information
that we file with the SEC in other documents. This means that we can disclose
important information to you by referring to other documents that contain that
information. The information incorporated by reference is considered to be part
of this prospectus. Information contained in this prospectus and information
that we file with the SEC in the future and incorporate by reference in this
prospectus automatically updates and supersedes previously filed information. We
incorporate by reference the documents listed below and any future filings we
make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities
Exchange Act of 1934, prior to the sale of all the shares covered by this
prospectus.

         (1)      our Annual Report on Form 10-K for the year ended December 31,
                  2000;

         (2)      our Quarterly Report on Form 10-Q for the quarter ended March
                  31, 2001;

         (3)      our Current Report on Form 8-K as filed with the SEC on
                  July 5, 2001;

         (4)      all of our filings pursuant to the Exchange Act after the date
                  of filing the initial registration statement and prior to
                  effectiveness of the registration statement; and

         (5)      the description of our common stock contained in our
                  Registration Statement on Form 8-A dated July 12, 1999.

         You may request a copy of these documents, which will be provided to
you at no cost, by writing or telephoning us using the following contact
information:

                           Art Technology Group, Inc.
                           25 First Street
                           Cambridge, Massachusetts 02141
                           Attention: General Counsel
                           Telephone: (617) 386-1000


                                      -16-



                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS


ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

         The following table sets forth the various expenses to be incurred in
connection with the sale and distribution of the securities being registered
hereby, all of which will be borne by the registrant (except any underwriting
discounts and commissions and expenses incurred by the selling stockholders for
brokerage, accounting, tax or legal services or any other expenses incurred by
the selling stockholders in disposing of the shares). All amounts shown are
estimates except the Securities and Exchange Commission registration fee.

         Filing Fee - Securities and Exchange Commission...........  $    20
         Legal fees and expenses...................................  $ 7,500
         Accounting fees and expenses..............................  $ 7,500
         Miscellaneous expenses....................................  $   980
                                                                     -------
                  Total Expenses...................................  $16,000
                                                                     =======

ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Section 102 of the Delaware General Corporation Law allows a
corporation to eliminate the personal liability of directors of a corporation to
the corporation or its stockholders for monetary damages for a breach of
fiduciary duty as a director, except where the director breached his duty of
loyalty, failed to act in good faith, engaged in intentional misconduct or
knowingly violated a law, authorized the payment of a dividend or approved a
stock repurchase in violation of Delaware corporate law or obtained an improper
personal benefit. The registrant has included such a provision in its Amended
and Restated Certificate of Incorporation.

         Section 145 of the General Corporation Law of Delaware provides that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred in
connection with an action or proceeding to which he is or is threatened to be
made a party by reason of such position, if such person shall have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, in any criminal proceeding, if such person
had no reasonable cause to believe his conduct was unlawful; provided that, in
the case of actions brought by or in the right of the corporation, no
indemnification shall be made with respect to any matter as to which such person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the adjudicating court determines that such indemnification is
proper under the circumstances.

         Article Eighth of the registrant's Amended and Restated Certificate of
Incorporation provides that no director of the registrant shall be personally
liable for any monetary damages for any breach of fiduciary duty as a director,
except to the extent that the Delaware General Corporation Law prohibits the
elimination or limitation of liability of directors for breach of fiduciary
duty.

         Article Ninth of the registrant's Amended and Restated Certificate of
Incorporation provides that a director or officer of the registrant (a) shall be
indemnified by the registrant against all expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement incurred in connection with any
litigation or other legal proceeding (other than an action by or in the right of
the registrant) brought against him by virtue of his position as a director or
officer of the registrant if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
registrant, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful and (b) shall be
indemnified by the registrant against all expenses (including attorneys' fees)
and amounts paid in settlement incurred in connection with any action by or in
the right of the registrant brought against him by virtue of his position as a
director or officer of the registrant if he acted in good faith and in a manner
he reasonably believed to be in, or not opposed to, the best interests of the
registrant, except that no indemnification shall be made with respect to any
matter as to which such person shall have been adjudged to be liable to the
registrant, unless a court determines that, despite such adjudication but in
view of all of the


                                      II-1



circumstances, he is entitled to indemnification of such expenses.
Notwithstanding the foregoing, to the extent that a director or officer has been
successful, on the merits or otherwise, including, without limitation, the
dismissal of an action without prejudice, he is required to be indemnified by
the registrant against all expenses (including attorneys' fees) incurred in
connection therewith. Expenses shall be advanced to a director or officer at his
request, provided that he undertakes to repay the amount advanced if it is
ultimately determined that he is not entitled to indemnification for such
expenses.

         Indemnification is required to be made unless the registrant determines
that the applicable standard of conduct required for indemnification has not
been met. In the event of a determination by the registrant that the director or
officer did not meet the applicable standard of conduct required for
indemnification, or if the registrant fails to make an indemnification payment
within 60 days after such payment is claimed by such person, such person is
permitted to petition the court to make an independent determination as to
whether such person is entitled to indemnification. As a condition precedent to
the right of indemnification, the director or officer must give the registrant
notice of the action for which indemnity is sought and the registrant has the
right to participate in such action or assume the defense thereof.

         Article Ninth of the registrant's Amended and Restated Certificate of
Incorporation further provides that the indemnification provided therein is not
exclusive, and provides that in the event that the Delaware General Corporation
Law is amended to expand the indemnification permitted to directors or officers
the registrant must indemnify those persons to the fullest extent permitted by
such law as so amended.

ITEM 16. EXHIBITS

  EXHIBIT NUMBER                      DESCRIPTION
  --------------                      -----------

         4.1*      Amended and Restated Certificate of Incorporation of the
                   Registrant

         4.1(a)**  Certificate of Amendment to the Amended and Restated
                   Certificate of Incorporation of the registrant, effective
                   June 7, 2000

         4.2       Amended and Restated By-laws of the Registrant.

         5.1       Opinion of Hale and Dorr LLP

         23.1      Consent of Arthur Andersen LLP

         23.2      Consent of Hale and Dorr LLP, included in Exhibit 5.1 filed
                   herewith.

         24.1      Power of Attorney (see page II-4 of this Registration
                   Statement).

------------
*        Incorporated by reference to the Registrant's Registration Statement on
         Form S-1 (File No. 333-78333)
**       Incorporated by reference to the Registrant's Quarterly Report on Form
         10-Q for the quarter ended September 30, 2000.

ITEM 17. UNDERTAKINGS.

         ITEM 512(a) OF REGULATION S-K. The undersigned Registrant hereby
undertakes:

         (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
         the Securities Act of 1933, as amended (the "Securities Act");

                  (ii) To reflect in the prospectus any facts or events arising
         after the effective date of this Registration Statement (or the most
         recent post-effective amendment thereof) which, individually or in the
         aggregate, represent a fundamental change in the information set forth
         in this Registration


                                      II-2



         Statement. Notwithstanding the foregoing, any increase or decrease in
         the volume of securities offered (if the total dollar value of
         securities offered would not exceed that which was registered) and any
         deviation from the low or high end of the estimated maximum offering
         range may be reflected in the form of prospectus filed with the
         Commission pursuant to Rule 424(b) if, in the aggregate, the changes in
         volume and price represent no more than 20 percent change in the
         maximum aggregate offering price set forth in the "Calculation of
         Registration Fee" table in the effective Registration Statement; and

                  (iii) To include any material information with respect to the
         plan of distribution not previously disclosed in this Registration
         Statement or any material change to such information in this
         Registration Statement;

PROVIDED, HOWEVER, that paragraphs (1)(i) and (1)(ii) do not apply if the
information required to be included is a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the Registrant pursuant to Section 13 or Section 15(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), that are
incorporated by reference in this Registration Statement.

         (2) That, for the purposes of determining any liability under the
Securities Act, each post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at the time shall be deemed to be the initial BONA
FIDE offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

         ITEM 512(b) OF REGULATION S-K. The Registrant hereby undertakes that,
for purposes of determining any liability under the Securities Act, each filing
of the Registrant's annual report pursuant to Section 13(a) or 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in this Registration Statement shall be deemed to be a
new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial BONA
FIDE offering thereof.

         ITEM 512(h) OF REGULATION S-K. Insofar as indemnification for
liabilities arising under the Securities Act may be permitted to directors,
officers and controlling persons of the Registrant pursuant to the
indemnification provisions described herein, or otherwise, the Registrant has
been advised that in the opinion of the Securities and Exchange Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.


                                      II-3



                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-3 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on
July 5, 2001.

                           ART TECHNOLOGY GROUP, INC.


                           By: /s/ Joseph T. Chung
                               -----------------------------------------------
                               Joseph T. Chung
                               Chairman of the Board, Chief Technology Officer
                               and Treasurer


                        SIGNATURES AND POWER OF ATTORNEY

         We, the undersigned officers and directors of Art Technology Group,
Inc., hereby severally constitute and appoint Joseph T. Chung, Jeet Singh and
Linda Handman and each of them singly, our true and lawful attorneys with full
power to any of them, and to each of them singly, to sign for us and in our
names in the capacities indicated below the Registration Statement on Form S-3
filed herewith and any and all pre-effective and post-effective amendments to
said Registration Statement and generally to do all such things in our name and
behalf in our capacities as officers and directors to enable Art Technology
Group, Inc. to comply with the provisions of the Securities Act of 1933, as
amended, and all requirements of the Securities and Exchange Commission, hereby
ratifying and confirming our signatures as they may be signed by our said
attorneys, or any of them, to said Registration Statement and any and all
amendments thereto.

         Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed by the following persons in the
capacities indicated as of July 5, 2001.




        SIGNATURE                                     TITLE
        ---------                                     -----
                               

/s/ Jeet Singh                    Chief Executive Officer and Director (Principal
------------------------------    Executive Officer)
Jeet Singh

/s/ Joseph T. Chung               Chairman of the Board, Chief Technology Officer and
------------------------------    Treasurer (Principal Financial and Accounting Officer)
Joseph T. Chung


/s/ Scott A. Jones
------------------------------    Director
Scott A. Jones


/s/ Charles R. Lax
------------------------------    Director
Charles R. Lax


/s/ Thomas N. Matlack
------------------------------    Director
Thomas N. Matlack


/s/ Phyllis S. Swersky
------------------------------    Director
Phyllis S. Swersky



------------------------------    Director
Robert F. Walters




                                      II-4



                                  EXHIBIT INDEX


     EXHIBIT NUMBER                      DESCRIPTION
     --------------                      -----------

           4.1*       Amended and Restated Certificate of Incorporation of the
                      Registrant

           4.1(a)**   Certificate of Amendment to the Amended and Restated
                      Certificate of Incorporation of the registrant, effective
                      June 7, 2000

           4.2        Amended and Restated By-laws of the Registrant.

           5.1        Opinion of Hale and Dorr LLP.

           23.1       Consent of Arthur Andersen LLP

           23.2       Consent of Hale and Dorr LLP, included in Exhibit 5.1
                      filed herewith.

           24.1       Power of Attorney (see page II-4 of this Registration
                      Statement).

----------------------
*        Incorporated by reference to the Registrant's Registration Statement on
         Form S-1 (File No. 333-78333)
**       Incorporated by reference to the Registrant's Quarterly Report on Form
         10-Q for the quarter ended September 30, 2000.


                                      II-5