This book constitutes the refereed proceedings of the 5th International Conference on Web-Age Information Management, WAIM 2004, held in Dalian, China in July 2004. The 57 revised full papers and 23 revised short and industrial papers presented together with 3 invited contributions were carefully reviewed and selected from 291 submissions. The papers are organized in topical sections on data stream processing, time series data processing, security, mobile computing, cache management, query evaluation, Web search engines, XML, Web services, classification, and data mining.