This book constitutes the refereed proceedings of the 5th International Computer Science Conference, ICSC'99, held in Hong Kong, China, in December 1999. The 30 revised full papers presented together with 30 short papers were carefully reviewed and selected from 80 submissions. The book is divided into sections on information filtering, data mining, Web databases, user interfaces, modeling, information retrieval, workflow, applications, active networks, mobility and distributed databases, protocols, distributed systems, information retrieval and filtering, Web technologies, and e-commerce.