Meaningful experiences in civic engagement and community connectedness are transformative for young people, who often feel voiceless and excluded from decision-making in civic and social institutions. "Action civics" programs, such as Generation Citizen, offer a school-based civic engagement intervention that can empower youth and potentially improve health, wellbeing, and equity. The proposed research will test the causal effects of Generation Citizen on (1) changes in civic engagement and sense of community and (2) subsequent health and wellbeing among middle and high school students. We will use a cluster-randomized controlled trial design, assigning treatment status at the school level (N=50) and reaching more than 1,500 students. This project is uniquely positioned to address the impact of a civic intervention on health outcomes.