This book constitutes the refereed proceedings of the 9th International Conference on Parallel Computing, Euro-Par 2003, held in Klagenfurt, Austria in August 2003. The 109 revised full papers and 52 revised research note papers were carefully reviewed and selected from 338 submissions. The papers presented give a unique survey of the state of the art in parallel computing research, ranging from algorithms and software aspects to hardware and applications in various fields. Besides the more classical topics in parallel computing, new topics are addressed as well like peer-to-peer computing, distributed multimedia systems, and mobile and ubiquitous computing.