In this chapter, I trace the evolution of the influential field of interest group theory from the 1920s to the 1950s. Two consequential things happened in this empirically oriented literature. First, the social ontology introduced by pluralists and theorists of process could be taken as given, accepted as factual descriptions of the political process. Second, community was reconceptualized and relegated to the status of a presupposition, now under the name of "consensus," invoked as a restraint on group conflict and a foundation for modern political life without being a topic of debate in its own right. This provided the discipline of political science with the rudiments of what would become an influential and lasting behavioralist solution to the problem of social order.