This study examined coparenting in a sample of 177 two-parent families with firstborn adolescents by using annual home interview data from mothers, fathers, and adolescents. With a path-analytic approach and with earlier problem behaviors controlled for, coparenting conflict predicted relative increases in adolescent risky behavior over 2 years. In addition, evidence for 2 types of mediation was found. Marital love mediated the link between adolescents' early risky behavior and coparenting 1 year later, and coparenting conflict mediated the link between marital love and adolescents' risky behavior 1 year later. Linkages did not emerge for coparenting cooperation or triangulation. Interventions that are focused on the marital and coparental relationships in families with adolescents may modify trajectories of adolescent risky behavior.