This book constitutes the refereed proceedings of the 11th International Workshop on Cooperative Information Agents, CIA 2007, held in Delft, The Netherlands, September 19-21, 2007.

The 19 revised full papers presented together with 4 invited papers were carefully reviewed and selected from 38 submissions. The papers are organized in topical sections on Information Search and Processing, Applications, Rational Cooperation, Interaction and Cooperation and Trust.