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, USA, in 2007. It was an associated event of AAMAS 2007, the conference on autonomous agents and multi-agent systems. The 11 full papers, together with 1 keynote lecture and 2 invited papers from the AAMAS main conference were carefully selected and substantially enhanced after the workshop.