This volume contains the Proceedings of the Fourth International Conference on Coordination Models and Languages, Coordination 2000. It was held in the wake of three successful earlier conferences whose proceedings were also p- lished in this series, in volumes 1061, 1282 and 1594. The need for increased programmer productivity and rapid development of complex systems provides pragmatic motivation for the development of coordination languages and m- els. The intellectual excitement associated with such endeavors is rooted in the decades-old desire to cope with increasingly higher levels of abstraction. Coordination-based methods provide a clean separation between individual so- ware components and their interactions within the overall software organization. This separation promises to make application development more tractable, to support global analysis, and to enhance software reuse. These are indeed major concerns in the information age, at a time when all aspects of society are relying, to an ever increasing degree, on software systems of unprecedented complexity. Research on coordination methods is likely to play a central role in addressing these technological concerns by changing the software culture around us and by leading to the development of e?ective technical solutions for a broad range of important problems.