This book constitutes the proceedings of the 39th IFIP WG 6.1 International Conference on Formal Techniques for Distributed Objects, Components, and Systems, FORTE 2019, held in Copenhagen, Denmark, in June 2019, as part of the 14th International Federated Conference on Distributed Computing Techniques, DisCoTec 2019. The 15 full and 3 short papers presented were carefully reviewed and selected from 42 submissions. The conference is dedicated to fundamental research on theory, models, tools, and applications for distributed systems.