This paper is about the design and implementatbn of a repllwted database that forms the basis for the N&s* gray, communication system The system supports groups of people working on shared sets of donunents and is intended jor use in a perso~ l computer network enulronment in which the database servers are'tarely connected". Most algorithms for guamnteetng amsistency across repllcas require more reliable network amnectbns between serwrs for adequate performance. Analysis of many group oommunkatfon applicatbns, however, revealed relatlwly weak consistency requirements across copies of the database. These requirements can be met by a simple replication algorlthrn that works well in rarely connected environments. TRls kind of replication has been used prevfously for a limited set of applications such as name directory replicatfon: we haw applied this technique to a much larger class of applfcatlons. Our characterfzatbn ojthfs class of applications suggests that this technique generalizes to support dfstrlbuted database Lmple-mentatlons of other gray, Luork systems, tncluding computer oonfeenclng and bulletin board systems.