This book constitutes the thoroughly refereed post-proceedings of the Second International Workshop on Argumentation in Multi-Agent Systems held in Utrecht, Netherlands in July 2005 as an associated event of AAMAS 2005, the main international conference on autonomous agents and multi-agent systems.

The 10 revised full papers presented together with an invited paper were carefully reviewed and selected from 17 submissions. The papers are organized in topical sections on foundations, negotiation, protocols, deliberation and coalition formation, and consensus formation.