This book constitutes the refereed proceedings of the 15th European Symposium on Programming, ESOP 2006, held in Vienna, Austria in March 2006 as part of ETAPS. The 21 revised full papers presented together with 2 invited talks were carefully reviewed and selected from 87 submissions. The papers address fundamental issues in the specification, analysis, and implementation of programming languages and systems; they are organized in topical sections on types for implementations, proof and types, verification and reasoning, security and distribution, analysis and verification, and connecting to the world.