This book constitutes the refereed proceedings of the 13th International Workshop on Enterprise and Organizational Modeling and Simulation, EOMAS 2017, held in Essen, Germany, in June 2017.  The main focus of EOMAS is on the role, importance, and application of modeling and simulation within the extended organizational and enterprise context. The 12 full papers presented in this volume were carefully reviewed and selected from 26 submissions. They were organized in topical sections on formal methods, conceptual modeling, and enterprise engineering. .