This study investigated trajectories of time spent in structured activities from middle childhood to early adolescence by using data from the National Institute of Child Health & Human Development (NICHD) Study of Early Child Care. We used latent class growth analyses and identified five trajectories (stable low, increasing high, decreasing low, decreasing moderate, and increasing moderate). Girls were overrepresented in the higher-involvement trajectories. Higher aggression levels predicted group membership in the increasing high trajectory compared to the remaining four trajectories. Lower delinquency levels differentiated the increasing high members from the decreasing low members. Additionally, higher family income predicted group membership across all five trajectories. Maternal education predicted group membership across the five trajectories. The findings suggest (a) groups of children follow distinct trajectories of time spent in structured activities and (b) gender, aggression, delinquency, family income, and maternal education predict group membership. (Contains 5 tables and 1 figure.)