This volume constitutes the refereed proceedings of the 5th International Conference on Mathematics of Program Construction, MPC 2000, held in Ponte de Lima, Portugal, in July 2000. The 12 revised full papers presented were carefully reviewed and selected for inclusion in the book. Also presented are three invited contributions. The papers address issues of programming methodology, program specification, program transformation, programming paradigms, programming calculi, and programming language semantics from the mathematical and logical point of view.