This book constitutes the refereed proceedings of the 18th International Conference on Architecture of Computing Systems, ARCS 2005, held in Innsbruck, Austria in March 2005.The 18 revised full papers presented were carefully reviewed and selected from 52 submissions. The papers are organized in topical sections on adaptation, power consumption, and scheduling; adaptation and agents; adaptation and services; application of adaptable systems; and pervasive computing and communication.