This study examines community service effects on adolescents’ prosocial behaviors as mediated through experiences made during service. Based on theoretical assumptions by Youniss and Yates, we suggest that personal agency experiences and being confronted with situations that can challenge the own world views (ideology experiences) serve as mediators. The data were collected in a two-wave longitudinal study surveying 2,408 German adolescents aged between 14 and 15 years. Based on true intraindividual change models, the results support the expected mediation of service effects on prosocial behaviors through agency, but not ideology experiences. The findings suggest that community service affects prosocial behaviors through a behavioral pathway.