This book constitutes the refereed proceedings of the 13th European PVM/MPI Users' Group Meeting held in Bonn, Germany in September 2006.The 38 revised full papers presented together with abstracts of 6 invited contributions, 4 tutorial papers and 6 poster papers were carefully reviewed and selected from 84 submissions. The papers are organized in topical sections on collective communication, communication protocols, debugging and verification, fault tolerance, metacomputing and grid, parallel I/O, implementation issues, object-oriented message passing, limitations and extensions, performance, and are completed with 6 contributions to the special ParSim session on current trends in numerical simulation for parallel engineering environments.