This paper describes an ecological model of the behavior of social entities in a property space defined by sociodemographic dimensions. The model departs from the standard population ecology model in that it measures dimensions of the niche space, and assembles populations into a community. In this model, the time and energy of human individuals are the resource consumed by the social entities. While the model was originally developed for voluntary organizations, the paper argues that this model can be applied to a very wide variety of social phenomena, including firms, groups, associations, events, cultural artifacts, markets, social circles, collectivities, occupations, social movements, roles, identities, attitudes, beliefs, lifestyles, institutions, meanings, human cognitive structure, disease and other socially transmissible quantities. The paper concludes with some speculations based loosely on the model. Copyright 2004, Oxford University Press.
