This book constitutes the refereed proceedings of the 13th International Conference on Integrated Formal Methods, IFM 2017, held in Turin, Italy, in September 2017. The 24 full papers and 4 short papers presented were carefully reviewed and selected from 61 submissions. They are organized in topical sections on cyber-physical systems, software verification tools, safety-critical systems, concurrency and distributed systems, program verification techniques, formal modeling, and verified software.