CONTEXT: Existing literature suggests that stepfather relationships may be associated with adolescents’ attitudes toward sex. Given the large number of children living with stepfathers, these associations call for the attention of researchers and intervention programs.

METHODS: Attitudes toward sex among participants in the first wave (1994–1995) of the National Longitudinal Study of Adolescent Health (Add Health) who were living in households headed by biological mothers and stepfathers were analyzed using linear regression models. Parental involvement and maternal attitudes toward sex were included as predictors.

RESULTS: The greater the involvement between adolescents and their stepfathers, the less positively disposed adolescents are toward having sex; however, the association holds only for males. Females’ dispositions toward sex are tied to their religiosity and their mothers’ attitudes toward sex. Both males and females who are sexually experienced view sex more positively than do those who have never had sex.

CONCLUSIONS: Different factors influence males’ and females’ motivations to engage in sex, and intervention programs need to be structured with these differences in mind. Programs that work toward cultivating close relationships between stepfathers and stepchildren will likely be most effective for males, while programs that highlight the important role that mothers play in making clear their beliefs about the acceptability of teenagers’ sexual activity will likely be most effective for females.