Previous research has shown that participation in extracurricular activities in high school can promote desirable outcomes, such as educational attainment and reduced problem behaviors, but little attention has been paid to relations with psychological indicators of positive youth development (PYD). Moreover, the potential importance of the degree to which young people find such engagement personally meaningful toward these relations has been overlooked. This study investigated longitudinal relations among extracurricular participation and multiple indicators of positive development in adolescence, and explored whether personal meaningfulness of these domains moderated these relations. Results showed that positive development was positively associated with participation in student leadership and volunteering, and negatively associated with participation in the creative arts. Additionally, many of the relations among extracurricular participation and positive development were moderated by activity meaningfulness, typically in the negative direction. The discussion highlights future directions for research on extracurricular participation, meaningful engagement, and PYD.