A large body of research has reported a positive relation between participation in extracurricular activities (ECA) and improved academic performance, social competence, and school engagement. This study explored the relation between ECA, social competence, and school engagement for students with and at risk of emotional and behavioral disorders (EBD). Specifically, the study addressed three research questions: (a) Is there a relation between participation in ECA and high school students with EBD's social competence and school engagement? (b) Is the relation moderated by EBD status, race, gender, or special education status? And, (c) is there a direct link between participation in ECA and students' social competence and school engagement for youth with EBD? Eighty students with EBD and 21 typically developing students were included based on their participation in a larger study examining interventions for U.S. high school students with EBD. Participants were administered a battery of assessments at the end of the school year measuring ECA participation, social competence, and school engagement. We used regression and instrumental variable analyses to address the research questions. Results indicated statistically significant, positive relations between participation in ECA, social competence, and school engagement. Implications for research and practice are discussed.