This book constitutes the proceedings of the 20th International Conference on Software and Systems Reuse, ICSR 2022, held in Montpellier, France in June 2022. The 7 full papers and 2 short papers included in this book were carefully reviewed and selected from 29 submissions. The papers were organized in topical sections named: Code Recommendations and Ruse; Learning and Reuse; Evolution and Reuse; Quality, Longevity and Reuse.