AbstractTo assess childhood family influences on adolescent sexual activity, 69 boys were studied in sixth grade and again in tenth grade. Boys' self‐restraint in sixth grade was hypothesized to mediate the effects of family influences on number of sexual partners four years later. Family scores included observed family interaction patterns, sons' reports of parents' child‐rearing practices (rejection, support, child‐centered/indulgence), and household composition. In different models, Time 1 family scores and sons' self‐restraint accounts for 34 and 48 percent of the variance in sons' subsequent sexuality. As predicted, regression analysis revealed that restraint mediated family influence at Time 1 on the number of sexual partners at Time 2. Notably, intact family, supportive family and child‐centred/indulgent parenting were associated with T1 restraint which in turn, was associated with sexual activity. Additionally, family/parenting scores were directly associated with adolescents' sexuality. In discriminant analyses, family scores predicted boys' status as virgins/nonvirgins four year later with greater than 70% success. Discussion focuses on the nature of the family influences and the mechanisms by which they relate to adolescent male