["Journal of Research on Adolescence, Volume 36, Issue 3, September 2026. ", "\nAbstract\nPoor mental health among adolescents and young adults in the United States today is a critical concern. Sports team participation, combining physical activity and social belonging, may be an effective component of interventions to improve mental health among this population. This study examines both short and long‐term associations between sports team participation in adolescence and anxiety and depression from adolescence to young adulthood, using the Future of Families and Child Wellbeing Study, a population‐based longitudinal birth cohort study of urban US children. In this sample of 2766 young adults (52% female, Mage = 22.3), controlling for a rich set of child and family characteristics, including prior mental health, we found that frequent sports participation in adolescence (33% of the sample), compared to none, was associated with substantially lower depression and anxiety symptoms among all adolescents. We also found that sustained sports participation in adolescence was associated with a lower likelihood of depression in young adulthood, but only for young adult males. Exploring heterogeneity in associations further by race/ethnicity and socioeconomic status, the strongest associations were found among young adult males who are non‐Hispanic white and Latino, and from higher socioeconomic backgrounds. These results suggest sustained sports team participation throughout adolescence may be a valuable intervention component for improving mental health among adolescents and young adults.\n"]