This book constitutes the refereed proceedings of the 19th European Conference on Object-Oriented Programming, ECOOP 2005, held in Glasgow, UK, in July 2005. The 24 revised full papers, presented together with two invited papers by the recipients of the newly introduced AITO Dahl-Nygaard Prize, were carefully reviewed and selected from 172 submissions. The papers are organized in topical sections on Java, aspects and modularity, language design, program analysis, types, testing, and concurrency.