This book constitutes the refereed proceedings of the 9th European Workshop on Modelling Autonomous Agents in a Multi-Agent World, MAAMAW'99, held in Valencia, Spain in June/July 1999. The 18 revised full papers presented were carefully reviewed and selected for inclusion in the book. The papers are organized in sections on engineering aspects of multi-agent systems, multi-agent systems frameworks, languages and protocols, negotiation and cooperation, and formal methods.
