This book constitutes the thoroughly refereed post-proceedings of the two European Workshops on Model Driven Architecture - Foundations and Applications, MDAFA 2003, held in Twente, The Netherlands in June 2003, and MDAFA 2004 held in Linköping, Sweden in June 2004. The 15 revised full papers presented were carefully reviewed and selected from the lectures of both events for inclusion in the book. All aspects of systems and software design are addressed to understand the foundations of MDA, to share experience in applying MDA techniques and tools, and to outline future research directions.