In this paper, we argue that attempts to change social settings have been hindered by lack of theoretical advances in understanding key aspects of social settings and how they work in a dynamic system. We present a systems framework for understanding youths' social settings. We focus on three aspects of settings that represent intervention targets: social processes (i.e., patterns of transactions between two or more people or groups of people), resources (i.e., human, economic, physical, temporal resources), and organization of resources (i.e., how resources are arranged and allocated). We postulate that these setting aspects are in dynamic transaction with each other, resulting in setting outcomes. Discussion focuses on the implications of our theoretical framework for setting intervention.