This book constitutes the refereed proceedings of the 8th International Symposium on Component-Based Software Engineering, CBSE 2005, held in St. Louis, Missouri, USA in May 2005 as an adjunct event of ICSE 2005.The 21 revised full papers and 2 revised short papers presented were carefully reviewed and selected from 91 submissions. The papers are organized in topical sections on prediction analysis, and monitoring of system architecture; architecture and design of component-based systems; extra-functional system properties of components and component-based systems; and components at work.