Studied the joint influence of families, peers, and early antisocial behavior on early substance use (SU) from age 11 yrs, over a period of 7 yrs. 206 fourth graders from schools in the higher crime areas, were assessed at 4th and 5th grades, and at 12th grade. Data on SU and antisocial behaviors were collected from teachers, parents, boys, observers, and record data, through interviews, questionnaires, home observations, and videotaped tasks. Results show that the transition from middle to high school was a period of rapid growth in smoking for Ss with a prior history of low sociometric status. Deviant peer association in early adolescence mediated relation between active peer support for rule breaking and SU was associated with immediate rise in SU during transition to high school. Ineffective parental monitoring was causative in Ss’ involvement in a deviant peer network.