This carefully edited book constitutes the strictly refereed post-workshop proceedings of the 4th International Workshop on Agent Theories, Architectures, and Languages, ATAL'97, held in Providence, Rhode Island, USA, in July 1997. The 25 revised full papers presented were selected from a total of 76 submissions. The book is divided into sections on methodologies, architectures and infrastructures, coordination planning and monitoring, formal methods, theories, and architectures and methodologies. Like its predecessors published in the Intelligent Agents series, this volume specifically focuses on the relationships between the theory and the applications of agents.