There is relatively little information on the treatment effectiveness of child behavior-management programs with Spanish-speaking populations. Though there are several empirically supported treatments available in English, research on the applicability of these programs in Spanish is virtually nonexistent. This single-case study discusses the application of Parent-Child Interaction Therapy (PCIT) with a Spanish-speaking mother-child dyad to address the child's externalizing behavior problems. Both observational and parent self-report data are presented. Results suggest that PCIT was effective in increasing positive parent behaviors, decreasing child behavior problems, and reducing parental stress level. Implications for future clinical and research work with Spanish-speaking families are discussed. (Contains 3 figures and 2 tables.)