This book constitutes the thoroughly refereed postproceedings of the 14th International Symposium on Logic Based Program Synthesis and Transformation, LOPSTR 2004, held in Verona, Italy in August 2004. The 17 revised full papers presented were carefully selected and revised from 23 full paper and 11 extended abstract submissions. The papers are organized in topical sections on verification and analysis, theory and security, transformations, program development, termination, and program development and synthesis.