This book constitutes the refereed proceedings of the 21st International Conference on Architecture of Computing Systems, ARCS 2008, held in Dresden, Germany, in February 2008.

The 19 revised full papers presented together with 2 keynote papers were carefully reviewed and selected from 47 submissions. The papers cover a wide spectrum reaching from pre-fabrication adaptation of architectural templates to dynamic run-time adaptation of deployed systems with special focus on adaptivity and adaptive system architectures. The papers are organized in topical sections on hardware design, pervasive computing, network processors and memory management, reconfigurable hardware, real-time architectures, organic computing, and computer architecture.