This volume contains the proceedings of the 25th International Conference on Logic Programming (ICLP 2009). The conference took place in Pasadena, Ca- fornia during July 14-17, 2009. The ICLP series of conferences is aimed at p- viding a technical forum for presenting and disseminating innovative research results in the ?eld of logic programming. Theconference,whichwasco-locatedwiththeInternationalJointConference on Arti?cial Intelligence (IJCAI), featured technical presentations, tutorials, - vited talks, and a number of special events, including: - The 5th ICLP Doctoral Student Consortium - The Second Workshop on Answer Set Programming and Other Computing Paradigms (ASPOCP) - The 6th International Workshop on Constraint Handling Rules (CHR) - The 9th International Colloquium on Implementation of Constraint and LOgic Programming Systems (CICLOPS) - The 4th International Workshop on (Constraint) Logic Programming and Software Engineering (CLPSE) - The First Workshop on Commercial Users of Logic Programming (CULP) - Workshop on ISO Prolog - WG17 - The 19th Workshopon Logic-basedmethods in ProgrammingEnvironments (WLPE) Since the ?rst conference held in Marseilles in 1982, ICLP has been the p- miere international conference for disseminating research results in logic p- gramming. The present edition of the conference received 69 submissions in three categories:application, system and tool, and technical papers. From these, the ProgramCommittee selected 29 papers for presentation and inclusion in the proceedings. In addition, the committee selected nine short papers describing on-going research work, PhD theses and research project overviews for poster presentations and inclusion in the proceedings.

This book constitutes the thoroughly refereed post-proceedings of the 15th International Symposium on Logic Based Program Synthesis and Transformation, LOPSTR 2005, held in September 2005. The 10 revised full papers presented together with one invited talk were carefully selected and revised from 33 submissions. The papers are organized in topical sections on tools for program development, program transformations, and software development and program analysis.