The scope and types of nutrition services provided in substance abuse treatment programs has not been well defined nor has there been an attempt to determine if associations exist between the provision of nutrition services and substance abuse treatment outcomes. The objectives of this study were to assess the provision (use and extent) of nutrition education in substance abuse treatment programs in facilities that provide a single or two or more substance abuse treatment programs, and to determine the possible association between nutrition intervention and substance abuse treatment program outcome measures (defined as changes in Addiction Severity Index [ASI] composite scores). A descriptive, single, cross-sectional survey of registered dietitians with clinical nutrition program management responsibility (n=152) was used to define the use and extent of nutrition services in substance abuse treatment programs. Positive associations between nutrition services provided, particularly nutrition education services and substance abuse treatment program outcome measures, were detected. When group nutrition/substance abuse education was offered, ASI psychological and medical domain scores improved by 68% and 56%, respectively (P<.05). Individual nutrition/substance abuse education was a predictor of ASI family/social domain change scores improving by 99% (P<.05). In those programs where group nutrition/substance abuse education was offered, moderate to strong correlations with various nutrition education services were observed, specifically in individual nutrition/substance abuse education (r=0.51; P<.05), group normal/nutrition education (r=0.64; P<.01), and individual normal/nutrition education (r=0.46; P<.05). Substance abuse treatment programs offering group nutrition/substance abuse education offered significantly (P<.05) more nutrition services overall. Findings support the position that nutrition education is an essential component of substance abuse treatment programs and can enhance substance abuse treatment outcomes. Dietitians should promote and encourage the inclusion of nutrition education into substance abuse treatment programs.