Objective: To assess the impact of a parenting intervention, "Familias: Preparando la Nueva Generación" (FPNG), intended to support children, on parents heavy drinking. We hypothesized that parent participants of FPNG would reduce their heavy drinking at 1-year follow-up. Methods: Parents (N = 281) of middle school children from a large, low-income metropolitan area in the Southwest United States participated in a randomized control trial over 2 years. Results: A logistic regression analysis using the maximum likelihood test determined that at Wave 3, parents receiving FPNG reduced heavy drinking behaviors compared to parents in the youth-only condition (odds ratio = 0.86, p < 0.05). Conclusions: Participating in the parenting program can effectively curb heavy drinking behaviors in parents--an important mechanism through which one may expect changes in youth risk behavior. The practice, policy, and research implications of these unintended findings are promising to the overall effectiveness of a parenting intervention for Mexican-heritage families.