This longitudinal study investigated social capital as a way through which youths’ organized activities promote their future adjustment. Specifically, we examined social mediators of the associations between intensity, duration, and breadth of participation from age 14 to 17 and adjustment at age 18. Two social mediators were tested: support from the activity leader and social integration into the activity peer group. In addition, we examined how these mediation effects vary across gender. The sample consisted of 228 French Canadian adolescents (65 % girls). Youths were surveyed yearly from age 12 to 18. Controlling for prior adjustment at age 12, greater duration of participation from age 14 to 17 was associated with lower problematic alcohol use and higher civic engagement at age 18 through support from the activity leader. In addition, for boys only, greater duration of participation was associated with fewer subsequent depressive symptoms through social integration into the activity peer group. Overall, our results suggest that sustained participation allows youths to develop positive social experiences within organized activities, which, in turn, promote their future adjustment. Moreover, boys might benefit more from social experiences in organized activities than girls, at least with respect to depressive symptoms.
