This volume contains the 28 papers presented at ESOP 2004, the 13th European Symposium on Programming, which took place in Barcelona, Spain, March 29 31, 2004. The ESOP series began in 1986 with the goal of bridging the gap between theory and practice, and the conferences continue to be devoted to explaining fundamental issues in the speci?cation, analysis, and implementation of programming languages and systems. The volume begins with a summary of an invited contribution by Peter O Hearn, titledResources, ConcurrencyandLocalReasoning, andcontinueswith the 27 papers selected by the Program...