This book constitutes the proceedings of the 40th IFIP WG 6.1 International Conference on Formal Techniques for Distributed Objects, Components, and Systems, FORTE 2020, held in Valletta, Malta, in June 2020, as part of the 15th International Federated Conference on Distributed Computing Techniques, DisCoTec 2020.* The 10 full papers and 1 short paper presented were carefully reviewed and selected from 25 submissions. The conference is dedicated to fundamental research on theory, models, tools, and applications for distributed systems. *The conference was held virtually due to the COVID-19 pandemic. Chapter 'Conformance-Based Doping Detection for Cyber-Physical Systems' is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.