Using data from the National Education Longitudinal Study, the authors examined relations between educational, civic, and occupational success in young adulthood and the duration and intensity of participation in organized activities during high school. They also examined these relations as a function of sponsorship (i.e., school- vs. community-sponsored organized activities). They found that youths who participated in organized activities for 2 years demonstrated more favorable educational and civic outcomes in young adulthood than those who participated for 1 year. More intensive participation was also associated with greater educational, civic, and occupational success in young adulthood--particularly among youths who participated in activities for 2 years. Educational attainment often mediated the relations between temporal measures of participation and young adult civic and occupational outcomes. With the exception of analyses examining occupational success, findings varied little as a function of sponsorship. Of note, analyses revealed that both temporal measures of participation were positively associated with young adult outcomes as many as 8 years after high school. (Contains 7 tables and 9 footnotes.)