This study focused on the role of school-based required community service in promoting adolescents' prosocial behavior and intended future civic involvement when service is differentiated by types and by adolescents' perceived experience. A longitudinal data set of high school students (N = 603) was analyzed to investigate the developmental steps from types of service through intended civic behavior. Results showed that service involving direct interaction with people in need led students to judge that they had made contributions to sponsoring organizations and, consequently, altered their self-awareness. In turn, changed awareness enhanced reports of helping behavior toward strangers, which then led to the likelihood of future volunteering and of voting, working on a political campaign, and demonstrating for a cause. Additional causal analyses supported the directional sequence that began with service experiences, led to prosocial behavior, and eventuated in intended future civic involvement. (Contains 4 figures.)