This book constitutes the proceedings of the 18thInternational Conference on Principles and Practice of Multi-Agent Systems,PRIMA 2015, held in Bertinoro, Italy, in October 2015.

The 29 full papers and 24 short papers presented in thisvolume were carefully reviewed and selected from 94 submissions. The conferencebrings together active researchers, developers and practitioners from bothacademia and industry to showcase, share and promote research in severaldomains, ranging from foundations of agent theory and engineering aspects ofagent systems, to emerging interdisciplinary areas of agent-based research.