This book constitutes the proceedings of the 17th International Workshop on OpenMP, IWOMP 2021, held virtually in September 2021 and hosted by the High Performance Computing research group at the University of Bristol, UK.The 15 full papers presented in this volume were carefully reviewed and selected for inclusion in this book. The papers are organized in topical sections named: synchronization and data; tasking expansions; applications; case studies; and heterogenous computing and memory.Chapter 'FOTV: A Generic Device Offloading Framework for OpenMP' is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.