Borrowing a framework used to study adolescent peer groups, this chapter relates key findings from chapters in this volume to the status or reputation that peers accord a given organized activity, the tendency of activities to channel adolescents toward some relationships and away from others, and the context for peer interactions created within an activity. Then, a conceptual model is presented urging more careful consideration of specific features of a given activity and the peers who participate in them when examining peer effects on activity participants' psychosocial outcomes. (Contains 1 figure.)