This book constitutes the proceedings of the 18th International Workshop on OpenMP, IWOMP 2022, held in Chattanooga, TN, USA, in September 2022.The 11 full papers presented in this volume were carefully reviewed and selected for inclusion in this book from the 13 submissions. The papers are organized in topical sections named: OpenMP and multiple nodes; exploring new and recent OpenMP extensions; effectie use of advanced heterogeneous node architectures; OpenMP tool support; OpenMP and multiple translation units. Chapter "Improving Tool Support for Nested Parallel Regions with Introspection Consistency" is publshed Open Access and licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/).