Objective: The authors report the adaptive functioning of hyperactive and control children in southeastern Wisconsin (Milwaukee) followed to young adulthood. Method: Interviews with participants concerning major life activities were collected between 1992 and 1996 and used along with employer ratings and high school records at the young adult follow-up (mean = 20 years, range 19-25) for this large sample of hyperactive (H; n = 149) and community control (CC; n = 72) children initially seen in 1978-1980 and studied for at least 13 years. Age, duration of follow-up, and IQ were statistically controlled as needed. Results: The H group had significantly lower educational performance and attainment, with 32% failing to complete high school. H group members had been fired from more jobs and manifested greater employer-rated attention-deficit/hyperactivity disorder and oppositional defiant disorder symptoms and lower job performance than the CC group. Socially, the H group had fewer close friends, more trouble keeping friends, and more social problems as rated by parents. Far more H than CC group members had become parents (38% versus 4%) and had been treated for sexually transmitted disease (16% versus 4%). Severity of lifetime conduct disorder was predictive of several of the most salient outcomes (failure to graduate, earlier sexual intercourse, early parenthood) whereas attention-deficit/hyperactivity disorder and oppositional defiant disorder at work were predictive of job performance and risk of being fired. Conclusions: These findings corroborate prior research and go further in identifying sexual activity and early parenthood as additional problematic domains of adaptive functioning at adulthood. (Contains 5 tables.)