This book constitutes the refereed proceedings of the 6th International Conference on Fundamental Approaches to Software Engineering, FASE 2003, held in Warsaw, Poland, in April 2003.

The 20 revised full papers presented together with a keynote paper were carefully reviewed and selected from 89 submissions. The papers are organized in topical sections on software components, mobile computing, aspects and web applications, software measurements, formal verficiation, analysis and testing, and model integration and extension.