This volume constitutes the revised selected papers of the 6th International Workshop, DALT 2008, held as satellite workshop of AAMAS 2008, the 7th International Joint Conference on Autonomous Agents and Multiagent Systems, in Estoril, Portugal, on May 12, 2008.

Invited Papers.- Specifying and Enforcing Norms in Artificial Institutions.- Social Norm Emergence in Virtual Agent Societies.- A Distributed Normative Infrastructure for Situated Multi-agent Organisations.- Contributed Papers.- A Complete STIT Logic for Knowledge and Action, and Some of Its Applications.- Combining Multiple Knowledge Representation Technologies into Agent Programming Languages.- Model-Checking Strategic Ability and Knowledge of the Past of Communicating Coalitions.- JASDL: A Practical Programming Approach Combining Agent and Semantic Web Technologies.- Leveraging New Plans in AgentSpeak(PL).- Increasing Bid Expressiveness for Effective and Balanced E-Barter Trading.- Inductive Negotiation in Answer Set Programming.- Mental State Abduction of BDI-Based Agents.- Iterated Belief Revision in the Face of Uncertain Communication.- Abstracting and Verifying Strategy-Proofness for Auction Mechanisms.- Using Temporal Logic to Integrate Goals and Qualitative Preferences into Agent Programming.- Strategic Agent Communication: An Argumentation-Driven Approach.

This volume constitutes the revised selected papers of the 6th International Workshop, DALT 2008, held as satellite workshop of AAMAS 2008, the 7th International Joint Conference on Autonomous Agents and Multiagent Systems, in Estoril, Portugal, on May 12, 2008. The 12 papers, presented together with 3 invited papers, were carefully reviewed and selected from 14 submissions. The workshop provided a discussion forum to both (i) support the transfer of declarative paradigms and techniques to the broader community of agent researchers and practitioners, and (ii) to bring the issue of designing complex agent systems to the attention of researchers working on declarative languages and technologies.