Model-Driven Architecture (MDA) is an initiative proposedby the Object M- agement Group (OMG) for platform-generic software development. MDA s- arates the speci?cation of system functionality from the implementation on a speci?c platform. It is aimed at making software assets more resilient to changes caused by emerging technologies. While stressing the importance of modeling, the MDA initiative covers a wide spectrum of research areas. Further e?orts are required to bring them into a coherent approach based on open standards and supported by matured tools and techniques. Thisvolumecontainstheselectedpapersoftwoworkshopson Model-Driven Architecture - Foundations and Applications (MDAFA): MDAFA 2003 held at the University of Twente, Twente, The Netherlands, June 26-27, 2003, and MDAFA 2004 held at Linko ping University, Link oping, Sweden, June 10-11, 2004. The goal of the workshops was to understand the foundations of MDA, to share experience in applying MDA techniques and tools, and to outline future research directions. The workshops organizers encouraged authors of accepted papers to re-submit their papers to a post-workshop reviewing process; 15 of these papers were accepted to appear in this volume on MDA.