Knowledge sharing in communities has attracted much attention in the field of knowledge management in research and practice. In this paper we outline a view where the community lifecycle is supported at different stages. The central component of our framework is the community ontology SWRC+COIN that describes the typical structure of communities. We exemplarily show how communities in the academic domain can be detected automatically by means of analyzing information flow in a bibliographic Peer-to-Peer system and how the instantiated community knowledge base can be exploited to support cooperative work in the communities.