This book constitutes the refereed proceedings of the First International COST 264 Workshop on Networked Group Communication, NGC'99, held in Pisa, Italy in November 1999. The 20 revised full papers presented are carefully reviewed and selected from a total of 49 submissions. Among the topics addressed are communication protocols, multicast communication, communication architectures, large-scale virtual environments, group communication, group building, community computing, multicast routing, Internet services, interactive multimedia, telecommunication service management, etc