Several long-standing theories intersect in discussing the impact of community characteristics and of the mass media. The structural pluralism model popularized by Tichenor and his colleagues says that social structure influences how mass media operate in communities because they respond to how power is distributed in the social system, whereas the linear model says that the increasing size of a community's population leads to more social differentiation and diversity and corresponding increases in subcultures with their own beliefs, customs, and behaviors. Recently, there has been a concern about how changes in society have led to a decline in organizational activity and the network of relationships and trust that constitute “social capital.” This article examines the impact of population and diversity (using census data) on individuals’ media use, interpersonal discussion and civic engagement (measured in a national survey), and the relationship among these variables. Analysis of a structural model provides evidence that the “linear hypothesis” can be combined with structural pluralism, with size—measured by population—impacting diversity, which influences the relationships that people have with their community. Concurrently, social categories influence people's communication patterns and community relationships, and communication impacts civic engagement.