This book constitutes the refereed proceedings of the International Conference on Embedded and Ubiquitous Computing, EUC 2004, held in Aizu-Wakamatsu City, Japan, in August 2004. The 104 revised full papaers presented were carefully reviewed and selected from more than 260 submissions. The papers are organized in topical sections on embedded hardware and software; real-time systems; power-aware computing; hardware/software codesign and systems-on-chip; mobile computing; wireless communication; multimedia and pervasive computing; agent technology and distributed computing, network protocols, security, and fault-tolerance; and middleware and peer-to-peer computing.