This volume contains the proceedings of the 10th International Conference on Concurrency Theory (CONCUR'99) held in Eindhoven, The Netherlands, 24-27 August 1999. ThepurposeoftheCONCURconferencesistobringtogetherresearchers, - velopersandstudentsinordertoadvancethetheoryofconcurrencyandpromote its applications. Interest in this topic is continuously growing, as a consequence oftheimportanceandubiquityofconcurrentsystemsandtheirapplications, and of the scienti?c relevance of their foundations. The scope of CONCUR'99 covers all areas of semantics, logics and veri?cation techniques for concurrent systems. A list of speci?c topics includes (but is not limited to) concurrency-related - pects of: models of computation and semantic domains, process algebras, Petri nets, event structures, real-time systems, hybrid systems, stochastic systems, - cidability, model-checking, veri?cation techniques, re?nement techniques, term and graph rewriting, distributed programming, logic constraint programming, object-oriented programming, typing systems and algorithms, case studies, and tools and environments for programming and veri?cation. The ?rst two CONCUR conferences were held in Amsterdam (NL) in 1990 and 1991, the following ones in Stony Brook (USA), Hildesheim (D), Uppsala (S), Philadelphia (USA), Pisa (I), Warsaw (PL) and Nice (F). The proceedings have appeared in Springer LNCS, as Volumes 458, 527, 630, 715, 836, 962, 1119, 1243, and 1466.