Abstract: This study established the influence of parenting style, siblings, sexual partners and friends/peers interactions on adolescents` sexual attitudes and behaviours. A total of five hundred and forty secondary school adolescents from three senatorial districts in Oyo State were randomly involved in the study. Their ages ranged between 15 and 21 years with a mean age of 18.2 years and standard deviation of 4.2. The two instruments used were author-constructed questionnaires with 0.81 and 0.69 reliability coefficient, respectively. The data obtained were analysed using multiple regression analysis. The result indicated that significant relationship existed between parenting style, friends/peers interactions and sexual partners but not with siblings. The results further indicated that, a combination of the independent variables significantly predicted adolescent sexual attitudes and behaviours. Based on the findings, it was recommended that, those in the helping professions should take cognizance of those variables that have been found to influence adolescent sexual attitudes and behaviours.