This book constitutes the refereed proceedings of the 8th International Conference on Interactive Theorem Proving, ITP 2017, held in Brasilia, Brazil, in September 2017.

The 28 full papers, 2 rough diamond papers, and 3 invited talk papers presented were carefully reviewed and selected from 65 submissions. The topics range from theoretical foundations to implementation aspects and applications in program verification, security and formalization of mathematical theories.