This book constitutes the thoroughly refereed post-conference proceedings of the 25th International Symposium on Logic-Based Program Synthesis and Transformation, LOPSTR 2015, held in Siena, Italy, in July 2015. The 21 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 30 submissions. The aim of the LOPSTR series is to stimulate and promote international research and collaboration on logic-based program development. LOPSTR is open to contributions in all aspects of logic- based program development, all stages of the software life cycle, and issues of both programming-in-the-small and programming-in-the-large.