We consider the problem of coordination and control of large heterogeneous groups of agents distributed over the Internet in the context of Law-Governed Interaction (LGI) [2,5]. LGI is a mode of interaction that allows a group of distributed heterogeneous agents to interact with each other with confidence that an explicitly specified policy, called the law of the group, is complied with by everyone in the group. The originalLGI model supported only explicit groups, whose membership is maintained and controlled by a central server. Such a central server is necessary for applications that require each member of the group to know about the membership of the entire group. However, in the case where members do not need to know the membership of the entire group, such a centralserv er can become an unnecessary performance bottleneck, as group size increases, as well as a single point of failure. In this paper, we present an extension to LGI allowing it to support implicit groups, also called communities, which require no centralcon trol of any kind, and whose membership does not have to be regulated, and might not be completely known to anybody.