Organized activities have been championed as an important youth setting to nurture character development through childhood and adolescence, but scholars have yet to document the state of research on activities and youth character. Using guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-analyses Statement (PRISMA, Moher et al., PLoS Med 6(7):e1000097, 2009), this study conducts an extensive review of previous research in order to provide a comprehensive understanding of the various ways in which organized activities support moral and civic character development. Through database and backward and forward citation searches, 65 studies were deemed eligible between 1999 and 2019, with 44 studies on civic character and 21 studies on moral character. Relations between organized activity participation and character development were assessed by five key dimensions of activity participation (intensity, duration, breadth, type and quality of the activity), and by youth characteristics (e.g., age, family income, gender, motivation/engagement in the activity). Review of the character literature provides evidence for the positive relations between organized activities and youth’s concurrent and long-term moral and civic character development. For civic studies, findings suggest that the greater the intensity, duration, and breadth of participation, the more favorable youth character outcomes. For moral character, the type and quality of the activity setting appear to be particularly important for supporting development. Overall, findings suggest that moral and civic character development ought to be considered and intentionally nurtured within activities as two separate, yet complimentary dimensions of interpersonal character. Future research is needed that explores various mechanisms that explain these associations and examines variations by characteristics of youth.