This book originates from the IJCAI 2003 International Workshop on Multi-Agents for Mass User Support, MAMUS 2003, held in Acapulco, Mexico in August 2003. Besides revised selected workshop papers, the volume editors invited contributions by leading researchers in order to complete coverage of important aspects. The papers address major current issues of multi-agent technology and its applications to support mass users and society more generally by using social coordination mechanisms. The papers are organized into topical sections on the theoretical background, resource allocation algorithms, mass user support in traffic systems, game theoretic analysis, and architectures for social coordination mechanisms.