On behalf of the Organizing Committee I am pleased to present the proceedings of the 2005 Symposium on Component-Based Software Engineering (CBSE). CBSE is concerned with the development of software-intensive systems from reusable parts (components), the development of reusable parts, and system maintenance and improvement by means of component replacement and c- tomization. CBSE 2005, "Software Components at Work," was the eighth in a series of events that promote a science and technology foundation for achieving predictable quality in software systems through the use of software component technology and its associated software engineering practices. We were fortunate to have a dedicated Program Committee comprised of 30 internationally recognized researchers and industrial practitioners. We received 91 submissions andeach paper wasreviewedby at least three ProgramComm- tee members (four for papers with an author on the Program Committee). The entirereviewingprocesswassupportedbyCyberChairPro, theWeb-basedpaper submissionandreviewsystemdevelopedandsupportedbyRichardvandeStadt of Borbala Online Conference Services. After a two-day virtual Program C- mittee meeting, 21 submissions were accepted as long papers and 2 submissions were accepted as short papers.