Studies that distinguish parental monitoring (parent-driven behaviors) from parental knowledge often fail to find protective effects of monitoring on adolescent behavior problems. To answer whether parental monitoring is more strongly associated with adolescent behavior problems among adolescents who may need it most, this study applied group-based trajectory modeling to change in early- to mid-adolescent aggressive behavior problems and examined associations between parental monitoring with different subgroups. Three latent groups of adolescents were found: Low Aggression, Medium-Increasing Aggression, and High-Increasing Aggression. Results show that more maternal and paternal monitoring were associated with fewer adolescent aggressive behavior problems only for adolescents in the High-Increasing Group. This result suggests that parental monitoring is a protective factor against adolescent aggressive behavior problems for subgroups of adolescents who may need it most and less impactful for other adolescents.