Background: Oppositional defiant disorder (ODD) is considered to be a disorder of childhood, yet evidence suggests that prevalence rates of the disorder are stable into late adolescence and trajectories of symptoms persist into young adulthood. Functional outcomes associated with ODD through childhood and adolescence include conflict within families, poor peer relationships, peer rejection, and academic difficulties. Little examination of functional outcomes in adulthood associated with ODD has been undertaken. Method: Data for the present analyses come from a clinic referred sample of 177 boys aged 7-12 followed up annually to age 18 and again at age 24. Annual parental report of psychopathology through adolescence was used to predict self-reported functional outcomes at 24. Results: Controlling for parent reported symptoms of attention deficit hyperactivity disorder (ADHD), Conduct disorder (CD), depression and anxiety, ODD symptoms from childhood through adolescence predicted poorer age 24 functioning with peers, poorer romantic relationships, a poorer paternal relationship, and having nobody who would provide a recommendation for a job. CD symptoms predicted workplace problems, poor maternal relationship, lower academic attainment, and violent injuries. Only parent reported ODD symptoms and child reported CD symptoms predicted a composite of poor adult outcomes. Conclusion: Oppositional defiant disorder is a disorder that significantly interferes with functioning, particularly in social or interpersonal relationships. The persistence of impairment associated with ODD into young adulthood calls for a reconsideration of ODD as a disorder limited to childhood.