This study uses the National Longitudinal Survey of Adolescent Health data set to evaluate the long-term influence of school discipline and security on political and civic participation. We find that young adults with a history of school suspension are less likely than others to vote and volunteer in civic activities years later, suggesting that suspension negatively impacts the likelihood that youth engage in future political and civic activities. These findings are consistent with prior theory and research highlighting the long-term negative implications of punitive disciplinary policies and the role schools play in preparing youth to participate in a democratic polity. We conclude that suspension undermines the development of the individual skills and capacities necessary for a democratic society by substituting collaborative problem solving for the exclusion and physical removal of students. The research lends empirical grounds for recommending the reform of school governance and the implementation of more constructive models of discipline.