This volume contains the proceedings of the 17th International Conference on Concurrency Theory (CONCUR) held in Bonn, Germany, August 27–30, 2006. The purpose of the CONCUR conference series is to bring together researchers, developers and students in order to advance the theory of concurrency and promote its applications. Interest in this topic is continuously growing, as a consequence of the importance and ubiquity of concurrent systems and their applications and the scientific relevance of their foundations. The scope of CONCUR covers all areas of semantics, logics, and verification techniques for concurrent systems. Topics include basic models and logics of concurrent and distributed computation (such as process algebras, Petri nets, domain theoretic or game theoretic models, modal and temporal logics), specialized models or classes of systems (such as circuits, synchronous systems, real-time and hybrid systems, stochastic systems, databases, mobile and migrating systems, parametric protocols, security protocols), related verification techniques and tools (such as staff space exploration, model-checking, synthesis, abstraction, automated deduction, testing), and related programming models (such as distributed, constraint- or object-oriented, graph rewriting, as well as associated typesystems, static analyses, abstract machines, and environments). This volume starts with five invited papers covering the invited lectures and tutorials of the conference. The remaining 29 papers were selected by the Programme Committee out of 101 submissions after a very intensive reviewing and discussion phase. We would like to thank the members of the Programme Committee and the external reviewers for their excellent and hard work. The conference programme contained three invited lectures and two invited tutorials.