ATG Captures ''Product of the Year'' Honor; Customer Inter@ction Solutions Magazine Recognizes Technical Excellence and Vision of ATG KnowledgeCenter.

CAMBRIDGE, Mass. -- ATG (Art Technology Group, Inc., Nasdaq: ARTG), the software provider behind the Web's richest customer experiences, today announced that its ATG KnowledgeCenter was named 2004 "Product of the Year" by the editors of Customer Inter@action Solutions. Judges selected ATG KnowledgeCenter for its unique and innovative approach to self-and assisted-service communications.

The Customer Inter@action Solutions "Product of the Year" award is a premier industry recognition of excellence and innovation in the area of technology and communications. The primary criteria for judging were the delivery of significant and definable business benefits, together with the innovation and originality of the solution.

"We are honored that the editors at Customer Inter@ction Solutions have chosen ATG KnowledgeCenter as the product that is the driving force in the e-service industry," said Cliff Conneighton, senior vice president of marketing at ATG. "Companies around the world rely on ATG KnowledgeCenter as they increasingly turn to platforms that leverage internal knowledgebases and natural language processing that allow enterprises to provide better customer service solutions. ATG is proud to be recognized for its contributions and benefits delivered to the industry and end users in particular."

ATG KnowledgeCenter is a modular set of integrated, award-winning products designed to meet the specific needs of today's organizations. Unique features of the platform include enterprise scalability, true, seven level natural language processing (NLP), detailed analysis and reporting capabilities of the customer experience, multiple language support, and seamless integration with CRM systems.

"With its acquisition of Primus Knowledge Solutions, ATG has established itself as the absolute leader in the e-service sector, as it has been in the e-marketing and e-sales markets," said Nadji Tehrani, chairman of TMC and founder of Customer Inter@action Solutions. "Selecting the winners of this award continues to be a difficult and arduous procedure, as the editorial team spends countless hours studying applications and product capabilities from a multitude of vendors, and researching ROI from the end-user community."

"We are delighted to bestow upon ATG the 2004 "Product of the Year" Award in recognition of the company's dedication to providing the ultimate customer experience."

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 online, via email and messaging, and through contact centers. ATG has delivered category-leading commerce, marketing and customer service solutions to hundreds of the world's best-known brands including American Eagle Outfitters, Best Buy, Kingfisher, Neiman Marcus, Target, Washington Mutual, Friends Provident, Merrill Lynch, Wells Fargo, HSBC, A&E Networks, Warner Music, AT&T Wireless, T-Mobile, SBC, Yahoo!, France Telecom, Airbus, GE, Boeing, Philips, Procter & Gamble, Hewlett-Packard, American Airlines, InterContinental Hotels Group, US Army, and US Federal Aviation Administration. 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. 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 ATG's periodic reports and registration statements filed with the Securities and Exchange Commission. Risk factors related to the subject matter of this press release include the possibility that the company's product strategy may change; the company may not qualify it to be included in future awards or may not receive future awards; the need to adapt to rapid changes so products do not become obsolete; the possibility of errors in ATG's software products; non-responsiveness of the market to receipt of awards; the potential that the products will not deliver significant and definable business benefits to end users and the costs and risks associated with intellectual property infringement and litigation. ATG undertakes no obligation to update any of the forward-looking statements after the date of this press release.