This book constitutes the refereed proceedings of the 6th German Conference on Multiagent Systems Technologies, MATES 2008, held in Kaiserslautern, Germany, in September 2008 - co-located with the 31st German Conference on Artificial Intelligence, KI 2008.<BR>The 16 revised full papers presented together with 2 invited talks were carefully reviewed and selected from 35 submissions. The papers present and discuss the latest advances of research and development in the area of autonomous agents and multiagent systems ranging from theoretical and methodological issues to applications in various fields.