Using primary socialization theory and theory of planned behavior, this study examined how targeted parent-child communication against substance use and parents' references to the negative consequences of their own past substance use (from the youth's perspective) directly and indirectly relate to Latino and European American youth's external norms (e.g., injunctive and descriptive), internal beliefs (e.g., personal norms, attitudes, and refusal efficacy), and substance use. This study used cross-sectional survey data from 253 Latino and 308 European American (N = 561) 6th- to 8th-grade students. Targeted parent-child communication was related to higher levels of antisubstance-use perceptions, whereas parents' references to their own past use was related to lower levels of antisubstance-use perceptions. Ethnic differences emerged with respect to specific mediators. (Contains 2 figures and 1 table.)