Civic engagement was studied in relation to overall development in adolescence, emerging adulthood, and young adulthood to examine how earlier activity involvement and success in prior and concurrent age-salient domains of competence may contribute to 2 forms of civic engagement in adulthood (citizenship and volunteering). Data on 163 youth were drawn from a longitudinal study of competence in a normative, urban school sample. Results indicate that competence and activity involvement in adolescence predict citizenship and volunteering in adulthood, 10 to 15 years later. As hypothesized, however, the level of competence in developmentally salient domains in adolescence and emerging adulthood fully mediate the predictive significance of concurrent activity involvement for civic engagement outcomes in adulthood. Findings also suggest that citizenship and volunteering are distinct types of civic engagement that should be studied separately. (Contains 1 footnote and 4 tables.)