Book excerpt: This book constitutes the refereed proceedings of the 11th International Conference on Coordination Models and Languages, COORDINATION 2009, held in Lisbon, Portugal, in June 2009, as one of the federated conferences on Distributed Computing Techniques, DisCoTec 2009. The 14 revised full papers presented were carefully reviewed and selected from 61 submissions. The subject-matter is to explore the spectrum of languages, middleware, services, and algorithms that separate behavior from interaction, therefore increasing modularity, simplifying reasoning, and ultimately enhancing software development.