Enabling group communication is one of the major challenges for the future Internet. Various issues ranging from services and applications to prools and infrastructure have to be addressed. Moreover, they need to be studied from various angles and therefore involve skills in multiple areas. COST 264 was created on tribute to this international effort towards group communication and related technologies. The European COST framework is ideal for establishing a new community of interest, providing an open forum for ideas, and also supporting young researchers in the field. The COST264 action, officially started in late 1998, aims at leveraging the European research in this area and creating intensive interaction at the international level. To this purpose, COST264 decided to organize an annual technical workshop, the “International Workshop on Networked Group Communication”. NGC’99 in Pisa is the first event of the series. Despitethisbeingthe first workshop and despite the very short time between the Call for Papers and the deadline for submissions, and the other conflicting and more established events, the Call for Papers of NGC’ 99 was highly successful: we received 49 papers, of which 18 were selected to compose the basis of the technical program. We hope you will enjoy our paper selection, which is the VI Preface core of these proceedings, and addresses important issues in the research and development of networked group communication. In addition to refereed contributions, we scheduled two keynote speakers (Christophe Diot and Steve Deering), and four invited talks by Ken Birman (Cornell), Bob Briscoe (BT), Radia Perlman (SUN), Tony Speakman (CISCO).