IMDEA Software Institute’s researchers Manuel Hermenegildo and Pedro López, were the Program Committee chairs of the 26th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2016) held in Edinburgh, Scotland UK, September 6-8, 2016, co-located with 18th International Symposium on Principles and Practice of Declarative Programming, PPDP, and the 23rd. Static Analysis Symposium, SAS. The program can be found here. The International Symposium on Logic-Based Program Synthesis and Transformation aims to stimulate and promote international research and collaboration in logic-based program development in any language paradigm.