|Abstract||This paper tests a model of adolescent treatment engagement within a residential drug treatment setting. Using a modified Theory of Planned Behavior (Ajzen, 1991), the model incorporates prior drug use, attitudes, subjective norms, and perceived social support as predictors of intentions to resist drug use and treatment engagement. The current study addresses a gap in the literature assessing the adolescent treatment process by drawing on the literature assessing adult populations and emphasizing the importance of social influences for adolescents. The sample included 407 adolescent clients from 7 residential drug treatment centers across the U.S. who completed surveys regarding an evaluation of themselves and treatment at intake and again 30-45 days later. Structural Equation Modeling was conducted to test the proposed model. Moderation analyses by gender revealed that social influences affect the treatment process differently for males and females. Implications for treatment interventions and directions for future research are discussed in terms of the final model and the role of social influences for gender.