This book constitutes the thoroughly refereed post-conference proceedings of the 13th International Conference on Principles and Practice of Multi-Agent Systems, PRIMA 2010, held in Kolkata, India, in November 2010. The 18 full papers presented together with 15 early innovation papers were carefully reviewed and selected from over 63 submissions. They focus on practical aspects of multiagent systems and cover topics such as agent communication, agent cooperation and negotiation, agent reasoning, agent-based simulation, mobile and semantic agents, agent technologies for service computing, agent-based system development, ServAgents workshop, IAHC workshop, and PRACSYS workshop.