This book constitutes the proceedings of the 17th International System Design Language Forum, SDL 2015, held in Berlin, Germany, in October 2015. The 15 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 26 submissions. They are organized in topical sections named: smart cities and distributed systems; specification and description language; domain specific languages; goal modeling; use-case modeling; and model-based testing.