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