Objective: Parents' values about sexuality and about premarital sex play unique roles in the development of adolescents' sexual attitudes and behaviours. However, research is scarce on the role of consistent versus inconsistent values transmission. The purpose of the present study was to examine the association between parental consistency/inconsistency of values toward adolescents' premarital sexual activity and adolescents' own premarital sex attitudes and behaviours. Method: The full sample included 293 adolescents in the 9th through 12th grades (aged 13-19 years), primarily African American, Hispanic, and Caucasian, from three high schools in suburban and urban school districts in the Midwest of the USA. Results: First, analyses of variance (ANOVAs) were run to see where differences between groups may lie. A multivariate analysis of covariance (MANCOVA) was then run with parental values as independent factor, and the six sexuality variables (sexual attitude, frequency of oral sex, frequency of sexual intercourse, age of first sexual intercourse, number of sexual partners and personal sexual values) as dependents, while controlling for gender, grade and race differences. Univariate analyses were run to determine direction of effects. Results indicated that adolescent sexuality outcomes varied by consistency of parents' values. ANCOVA results revealed that adolescents' sexual attitudes, frequency of oral sex, frequency of sexual intercourse, and number of sexual partners all varied by parents' values status. Conclusion: Parental sexual attitudes and consistency in parental communication contribute significantly to successful development in young people.