The adolescent substance abuse (ASA) study collected information concerning drug use and psychopathology on male adolescent probands in treatment for substance abuse and also on matched control adolescents, as well as all available family members of both groups. Information was obtained through direct interview and the family history method of assessment. Both methods revealed greater alcohol and drug use, conduct disorder (CD) and antisocial personality disorder (ASP) in the relatives of treatment probands as compared with control relatives. These results suggest familial transmission, not only for alcohol abuse, but also for non-alcohol substance abuse. Familial transmission for CD and ASP is also evident for both male and female relatives, although the prevalence of these disorders is significantly greater in males than females.