This book constitutes the thoroughly refereed post-proceedings of the 4th International Workshop on Declarative Agent Languages and Technologies, DALT 2006, held in Japan in May 2006. This was an associated event of AAMAS 2006, the main international conference on autonomous agents and multi-agent systems. The 12 revised full papers presented together with one invited talk and three invited papers were carefully selected for inclusion in the book.

Invited Talk.- Producing Compliant Interactions: Conformance, Coverage, and Interoperability.- Invited Papers.- Towards Theory Translation.- The Complexity of Model Checking Concurrent Programs Against CTLK Specifications.- Dynamic Model Checking for Multi-agent Systems.- Contributed Papers.- Automating Belief Revision for AgentSpeak.- A Foundational Ontology of Organizations and Roles.- When Agents Communicate Hypotheses in Critical Situations.- A Fibred Tableau Calculus for Modal Logics of Agents.- Programming Declarative Goals Using Plan Patterns.- JADL - An Agent Description Language for Smart Agents.- Agreeing on Defeasible Commitments.- A Dynamic Logic Programming Based System for Agents with Declarative Goals.- A Collaborative Framework to Realize Virtual Enterprises Using 3APL.- A Modeling Framework for Generic Agent Interaction Protocols.- Plan Generation and Plan Execution in Agent Programming.- A Functional Program for Agents, Actions, and Deontic Specifications.