The present community membership data management system identifies each user and their associated communities of interest. Each community has a user defined permission to access a subset of the user's data, which data is shared among some or all of the members of that community. When the user's data is updated, the update is automatically propagated to all of the identified associated communities of interest and the members of those communities who have permission to receive that data. Thus, each user of the present community membership data management system has their computerized calendar and address book system automatically populated with data, which data is continuously and automatically updated. The confidentiality and security of the user data is maintained by defining a set of permissions among the communities, members of communities and for each user to ensure that the user maintains control of the propagation of their data. Each user therefore maintains a "virtual user image" in each of the communities, where the members of that community view only one aspect of the user's personal data.