This book constitutes the refereed proceedings of the 15th International SPIN workshop on Model Checking Software, SPIN 2008, held in Los Angeles, CA, USA, in August 2008. The 17 revised full papers presented together with 1 tool paper and 4 invited talks were carefully reviewed and selected from 41 submissions. The main focus of the workshop series is software systems, including models and programs. The papers cover theoretical and algorithmic foundations as well as tools for software model checking and foster interactions and exchanges of ideas with related areas in software engineering, such as static analysis, dynamic analysis, and testing.