This book constitutes the refereed proceedings of the 10th IFIP/IEEE International Workshop on Distributed Systems: Operations and Management, DSOM'99, held in Zurich, Switzerland in October 1999 with the topical focus on Active Technologies for Network and Service Management.The 20 revised full papers presented were carefully reviewed and selected from more than 50 submissions. The papers are organized in topical sections on decentralized monitoring and anomaly detection, management components and multi-domain management, the future of SNMP-based management, programmable SNMP-based management, management of programmable and active networks, IT and enterprise management, and management tools.