African American couples (N = 139; 67.7% married; with children between the ages of 9 and 14) were randomly assigned to (a) a culturally sensitive, couple- and parenting-focused program designed to prevent stress-spillover (n = 70) or (b) an information-only control condition in which couples received self-help materials (n = 69). Eightmonths after baseline, youth whose parents participated in the program, compared with control youth, reported increased parental monitoring, positive racial socialization, and positive self-concept, as well as decreased conduct problems and self-reported substance use. Changes in youth-reported parenting behavior partially mediated the effect of the intervention on conduct problems and fully mediated its impact on positive self-concept, but did not mediate effects on lifetime substance use initiation. Results suggest the potential for a culturally sensitive family-based intervention targeting adults' couple and parenting processes to enhance multiple parenting behaviors as well as decrease youths' substance use onset and vulnerability.