An ultimate goal of both formal and informal educational opportunities during adolescence is to prepare young people to be responsible and productive members of society. Being a responsible and productive citizen includes being civically engaged, and there is growing scholarly awareness that civic engagement includes actions (e.g., voting, volunteering, environmental behavior) as well as dispositions. As adolescents transition to adulthood, many leave behind institutionalized civic education, yet we know considerably less about informal educational opportunities (e.g., experiences and relationships) that socialize civic engagement in young adulthood. Using nationally representative longitudinal cohort sequential data from Monitoring the Future, this proposal aims to (1) describe complex, meaningful patterns of developmental change in multiple forms of civic engagement (i.e., social responsibility, volunteering, political actions), (2) identify experiences in high school and across young adulthood that predict developmental change in civic engagement, and (3) investigate variations in developmental patterns and correlates of civic engagement across social groups (e.g., socioeconomic status, ethnicity) and three decades of historical cohorts. This research brings together a unique interdisciplinary collaborative team, and our work is poised to inform applied research and policy efforts to improve civic education during the transition to adulthood.