Background: The aim of the study was to clarify the developmental risk associated with hyperactive behaviour in girls in a longitudinal epidemiological design. Methods: This was investigated in a follow-up study of girls who were identified by parent and teacher ratings in a large community survey of 6- and 7-year-olds as showing pervasive hyperactivity or conduct problems or the comorbid mixture of both problems or neither problem. They were later investigated, at the age of 14 to 16 years, with a detailed self-report interview technique. Results: Hyperactivity was a risk factor for later development, even allowing for the coexistence of conduct problems. Hyperactivity predicted academic problems and interpersonal relationship problems. Relationships with parents, by contrast, were not portrayed to be as problematic as relationships with peers and the opposite sex. Their psychological, social and occupational functioning was objectively rated to be more deviant and their self-report showed them to be more ambivalent about their future. There was a trend for hyperactivity to be self-reported as a risk for the development of continuing symptomatology but neither hyperactivity nor conduct problems were self-reported to be a risk for antisocial behaviour, substance misuse or low self-esteem in adolescence. However, they were at risk for the development of state anxiety. Conclusions: The results suggested girls' pattern of functioning may differ from that of boys because girls self-report a more pervasive range of social dysfunction than that previously reported in boys.