ATG Launches New Version of Web Self-Service Offering, Integrating Primus Search Solution.

CAMBRIDGE, Mass. -- ATG Adaptive Customer Assistance 2005 Combines Technology from Both ATG and Primus to Deliver a Complete Web Self-Service Solution

ATG (Art Technology Group, Inc., NASDAQ: ARTG), the software provider behind the most consistent and relevant marketing, commerce, and customer service experiences, today announced the general availability of ATG Adaptive Customer Assistance 2005, a complete Web self-service solution that combines ATG's transaction and personalization technology with award-winning search technology from Primus Knowledge Solutions, Inc. ATG acquired Primus in November, 2004.

"We have been working aggressively on the integration of our software solutions with those we acquired from Primus," said Ken Volpe, ATG's senior vice president for products and technologies. "Our complementary product lines make the integration process seamless, and we're now seeing the first fruits of our vision, confirming that our e-service strategy is on target."

ATG Adaptive Customer Assistance (ACA), unlike other Web self-service products on the market, allows Web visitors to ask questions and receive answers that include not only text, but also personal transaction information (such as account balances) and links to other relevant documents. Answers provided by ACA can be much more specific, relevant, and useful to the customer because they are guided by what is known about the visitor (via segmentation, demographics, or previous transaction history). These unique attributes earned ACA an "Editor's Choice" award as a trend-setting product for 2004, by KMWorld magazine.

ACA 2005 is powered by ATG Search, (formerly known as Primus Enterprise Search), which provides relevant answers for customer support, shopping cart questions, and general site inquiries, and enhances the customer experience as a result. The product's advanced NLP technology performs all seven levels of analysis on both content and query, to consistently deliver the best answer. Result sets are populated with answers extracted from Web content, knowledge bases, forums, and documents, providing one-click answer resolution.

"ATG's vision is to create a single platform that provides a more relevant, consistent, interactive experience across the lifecycle from marketing to commerce and customer service, and across the channels of the Web, e-mail and call center," said Cliff Conneighton, ATG senior vice president of marketing. "The combined ATG and Primus products are so inherently complementary that we plan to support and advance every current major product line from both companies, while thoroughly integrating them. ATG plans to make additional announcements and continued enhancements and integrations throughout 2005."

ACA is used by companies as diverse as InterContinental Hotels Group and MovieLink, while the search technology acquired from Primus is used by global leaders including AT&T Wireless, Washington Mutual, Tyson Foods, RCN Telecom, and Hitachi Data Systems.

"Organizations are moving to multi-channel self-service solutions where the knowledge base and business rules can be created and maintained once, and leveraged across all channels (for example, e-mail, interactive voice response, or Short Message Service)," said Esteban Kolsky, research director, Gartner. "In addition, there is a move to consolidate informational and transactional self-service functions."

ACA 2005 is now shipping and generally available.

About ATG

ATG (Art Technology Group, Inc., NASDAQ: ARTG) delivers innovative software to help high-end consumer-facing companies create a richer, more adaptive interactive experience for their customers and partners throughout the lifecycle of marketing, commerce, and customer service, and across the Web, e-mail and call centers. ATG has delivered category-leading e-business solutions to many of the world's best known brands including A&E Networks, American Airlines, AT&T Wireless, Best Buy, France Telecom, Friends Provident, Hewlett-Packard, InterContinental Hotels Group, Kingfisher, Merrill Lynch, Neiman Marcus, Philips, Procter & Gamble, Target, US Army, US Federal Aviation Administration, Warner Music, and Wells Fargo. The company is headquartered in Cambridge, Massachusetts, with additional locations throughout North America, Europe, and Asia. For more information about ATG, please visit www.atg.com.

(C) 2005 Art Technology Group, Inc. ATG and Art Technology Group are registered trademarks of Art Technology Group, Inc., and ATG Adaptive Customer Outreach ATG Adaptive Customer Assistance are its service marks. All other product names, service marks, and trademarks mentioned herein are trademarks of their respective owners.

This press release contains forward-looking statements for purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. These statements involve known and unknown risks and uncertainties that may cause ATG's actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statements. Important risk factors affecting ATG's business generally may be found in their periodic reports and registration statements filed with the Securities and Exchange Commission at www.sec.gov. Risk factors related to the subject matter of this press release include the possibility that the ATG product deployment will not be successful, on time or significantly enhance the user's Internet experience; that those customers leveraging ATG won't have the opportunity to increase revenue and decrease future costs; ATG's need to adapt to rapid changes so products do not become obsolete; the possibility of errors in ATG's software products; that the ATG product will not continue to be integrated with third party applications servers or will not support all Web services enabled systems; that ATG's product strategy may change in the future; that ATG may discontinue marketing and licensing the product; and the risks and costs of intellectual property litigation. ATG undertakes no obligation to update any of the forward-looking statements after the date of this press release.