ATG Receives Highest Rating in Research Firm's ERMS MarketScope - ATG Receives ''Strong Positive'' Rating for ERMS MarketScope.

CAMBRIDGE, Mass. -- ATG (Art Technology Group, Inc., NASDAQ: ARTG) the software provider behind the most consistent and relevant marketing, commerce, and service experiences, today announced that the company has received the highest rating in the Gartner E-mail Response Management Systems MarketScope. ATG scored a "Strong Positive" rating.

The report, issued on January 6, 2005, is authored by Gartner Research Director Esteban Kolsky. In the report, he evaluates 15 vendors that offer e-mail communication management solutions. In the ERMS MarketScope framework, Gartner calls out "Strong Positive" vendors as "solid providers of strategic products, services or solutions." They advise current customers of the solutions to "continue investments," and they ask that potential customers "consider this vendor a strong strategic choice."

"As the volume of email in the enterprise grows and grows, email communication continues to emerge as a critical element of today's business infrastructure," said Cliff Conneighton, vice president of marketing, ATG. "Clearly ATG provides the best solution on the market designed from the ground up to enable both inbound and outbound electronic communications with customers. ATG Communication Center reduces the cost structure for customer service, provides faster response times, improves customer satisfaction, and allows for rapid ROI. We're delighted to receive this placement from a premier industry research firm."

To view the Gartner ERMS MarketScope, visit http://mediaproducts.gartner.com/reprints/atg/124088.html

To learn more about ATG Communication Center, visit http://www.atg.com/en/products/communication_center.jhtml

The MarketScope is copyrighted 1/6/2005 by Gartner, Inc. and is reused with permission. The MarketScope is an evaluation of a marketplace at and for a specific time period. It depicts Gartner's analysis of how certain vendors measure against criteria for that marketplace, as defined by Gartner. Gartner does not endorse any vendor, product or service depicted in the MarketScope, and does not advise technology users to select only those vendors with the highest rating. Gartner disclaims all warranties, express or implied, with respect to this research, including any warranties of merchantability or fitness for a particular purpose

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. Any forward-looking statements contained in this release are based on current expectations, are not guarantees of future performance and are subject to a number of 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. Risk factors related to the subject matter of this press release include the following: the possibility that ATG's product strategy may change; the need to adapt to rapid changes so ATG products do not become obsolete; the possibility of errors in ATG's products; risk that ATG products will not deliver significant and definable business benefits to end users; difficulties encountered in the integration, deployment, or implementation of the ATG products and customers systems; failure in the customer's widespread adoption and use of the ATG products; risk resulting from new product introductions and customer acceptance of new ATG products; fluctuations in customer demand; use of the Internet as a vehicle for ATG products; risks associated with competition and the rapid consolidation of competitors; the ability of ATG to manage its growth and integration efforts and the ability of ATG to compete successfully in the future; non-responsiveness of the market to receipt of awards; the company may not qualify it to be included in future awards or may not receive future awards; costs and risks associated with intellectual property infringement and litigation, as well as other 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, including but not limited to those appearing under the caption "RISK FACTORS THAT MAY AFFECT RESULTS". ATG undertakes no obligation to update any of the forward-looking statements after the date of this press release.