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.