This book constitutes the proceedings of the 26th European Symposium on Programming, ESOP 2017, which took place in Uppsala, Sweden in April 2017, held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2017. The 36 papers presented in this volume were carefully reviewed and selected from 112 submissions. They cover traditional as well as emerging topics in programming languages. In detail they deal with semantic foundation and type system for probabilistic programming; techniqu3es for verifying concurrent or higher-order programs; programming languages for arrays or web data; program analysis and verification of non-standard program properties; foundation and application of interactive theorem proving; graph rewriting; separation logic; session type; type theory; and implicit computational complexity.