This book constitutes the refereed proceedings of the 4th International Symposium on Parallel and Distributed Processing and Applications, ISPA 2006, held in Sorrento, Italy in November 2006.

The 79 revised full papers presented together with 5 keynote speeches were carefully reviewed and selected from 277 submissions. The papers are organized in topical sections on architectures, networks, languages, algorithms, middleware, cooperative computing, software, and applications.