The concept of a “focus of activity” was developed to describe the nature of non-network social structures that often underly the formation of intersecting clusters of ties in large-scale social networks. The primary purpose of the “focus theory” was to encourage network analysts to consider the impact of those underlying structures before attributing too much of the structure and consequences of social networks to psychological processes, individual choices, or self-contained network processes. We have been pleased to see that network researchers have increasingly considered the impacts of these non-network social structures. Nevertheless, we take this opportunity to clarify and extend the focus theory in ways that may make it more applicable and useful for more purposes. We show how the focus theory can be reconciled with some influential network theories that may initially appear inconsistent with it. We discuss how the focused organization facilitates indirect connections across large-scale social networks; and, we explicitly extend the focus theory by considering additional processes causing both the loss of old ties and the accumulation of new ties within clusters over time.