This book constitutes the refereed proceedings of the 9th International Workshop on Web Content Caching and Distribution, WCW 2004, held in Beijing, China, in October 2004.The 15 revised full papers and 6 revised short papers presented were carefully reviewed and selected from more than 50 submissions. The papers are organized in topical sections on placement and redirection, structured overlays, architectural issues, multimedia caching, caching in peer-to-peer systems, algorithms, systems management, and systems evaluation.