The current study examined the curvilinear links between involvement in organized activities (OA) and sport activities specifically and various indicators of psychological and social development. Participants included 150 9th and 10th graders (57% females) from an urban, selective-enrollment high school. Eligibility for admission is based on city residence, high GPA, and high scores on standardized tests and an admission exam. Findings indicated that benefits of OA involvement leveled off at approximately 5-7 h/week, with diminishing returns for adolescents participating in more than 10 h/week. Results also suggest that OA involvement uniquely impacts male and lower-income participants. Males reported threshold effects in terms of perceived friendship competence and depressive symptoms. Male sport participants and lower-income adolescents reported a similar pattern for loneliness. Findings suggest that among a high achieving sample of urban adolescents, social and psychological benefits are linked to moderate but not intense involvement in OAs and sports. (Contains 2 tables and 5 figures.)