This paper describes the theoretical and empirical foundations of Familias Unidas, a multilevel, family-centered intervention designed to prevent problem behavior in Hispanic adolescents. The main theoretical tenets for the intervention model; an ecological-developmental perspective, the centrality of ethnic and cultural themes, application of empowerment principles, and a family focus are reviewed. The literature on the risk and protective factors that provided the justification for the intervention's targeted mediators and the core clinical applications that are intended to alter them are discussed. Familias Unidas engages Hispanic immigrant parents into an empowerment process in which they first build a strong parent-support network and then use the network to increase knowledge of culturally relevant parenting, strengthen parenting skills, and then apply these new skills in a series of activities designed to reduce risks frequently found in poor, urban environments. The available evidence supporting the efficacy of Familias Unidas is summarized, as are future goals and a current, second-generation application of the intervention.