This book constitutes the thoroughly refereed post-proceedings of the Third International School and Symposium on Advanced Distributed Systems, ISSADS 2004, held in Guadalajara, Mexico in January 2004.The 25 revised full papers presented were carefully reviewed and selected from 46 submissions. Among the topics addressed are virtual characters, distributed toolkits, serial visual presentation, multi-agent architectures, MAS, agent-object hybrid languages, robot soccer agents, distributed querying, semantic search engines, coordination, distributed collaboration, virtual communities,...