This book constitutes the thoroughly refereed post-workshop proceedings of the 5th International Workshop on Declarative Agent Languages and Technologies, DALT 2007, held in Honolulu, HI, USA, in May 2007 as an associated event of AAMAS 2007, the main international conference on autonomous agents and multi-agent systems.

The 11 revised full papers presented together with 1 keynote lecture and 2 invited papers from the AAMAS main conference - substantially enhanced after the workshop - were carefully selected for inclusion in the book. The papers combine declarative and formal approaches with engineering and technology aspects of agents and multiagent systems and focus especially on modeling, goals, foundational concepts, and communication.