This study was designed to examine the paternal determinants of male adolescent marijuana use in the context of the mother-son and parental relationships. In addition, parental factors affecting experimental vs regular use of marijuana were examined. Two hundred forty-six male college students and their fathers were administered written questionnaires. Results indicated that the father's personality attributes and socialization techniques are associated with the son's use of marijuana despite control on the mother-son relationship. Fathers of marijuana users score higher on measures of psychopathology and unconventionality, and are less likely to have established close relationships with their sons. In addition, marijuana users more than nonusers have unaffectionate mothers and parents with less harmonious marital relations. Also of importance were interactions within the family system. The significance of these second-order effects highlights the importance of examining the father-son relation in the context of mother-son and parental interactions.