This study examined the influence of the traditional values held by Mexican heritage parents on the intention of their adolescent children to use drugs. Specifically, the study tested a mediation model in which the traditional cultural values of parents were hypothesized to influence adolescent drug use intentions indirectly by influencing ethnic identify and adolescent perceptions of parental injunctive norms against drug use. Parents reported on traditional cultural values and expectations for their child. Adolescents reported perceived reaction from parents if they used drugs (parental injunctive norms), ethnic identity, and their intention to use drugs in the future. Two direct effects were observed: parental values on expectations and parental injunctive norms on adolescent drug use intentions. Two paths were also moderated by the sex of the adolescent. The path from parent values to parent expectations was significantly stronger for adolescent girls than boys; the path from ethnic identity affirmation to drug intentions was protective for boys but not for girls. The negative relationship between perceived parental reaction and adolescent drug use intentions suggests that anti-drug norms communicated by parents had a protective influence and can deter youth from using drugs. The results of the current study did not support the hypothesized mediational model, but did provide additional support for the importance of parental influence on adolescents' plans and ideas about using alcohol, cigarettes, and marijuana. More research is necessary to examine the influence of culture and the mechanisms by which cultural values impact Mexican heritage adolescents' intentions to use drugs and subsequent use.