This volume contains the proceedings of the 19th International Conference on Concurrency Theory (CONCUR 2008) which took place at the University of TorontoinToronto, Canada, August19 22,2008. CONCUR2008wasco-located with the 27th Annual ACM SIGACT-SIGOPS Symposium on the Principles of Distributed Computing (PODC 2008), and the two conferences shared two invited speakers, some social events, and a symposium celebrating the lifelong research contributions of Nancy Lynch. The purpose of the CONCUR conferences is to bring together researchers, developers, and students in order to advance the...