This book constitutes the refereed proceedings of the International Conference on Architecture of Computing Systems, ARCS 2004, held in Augsburg, Germany, in March 2004. The 22 revised full papers presented together with the abstracts of two invited lectures were carefully reviewed and selected from 50 submissions. The papers are organized in topical sections on organic computing, peer-to-peer computing, reconfigurable hardware, hardware, wireless architectures and networking, and applications.