The importance and efficacy of formalized treatment for drug abuse and dependence, combined with high attrition rates in drug treatment settings, emphasizes the need for research to help understand what factors influence an individual’s decision to engage in treatment The purpose of this study was to test a model of treatment engagement in which the effects of psychiatric distress, family and social problems and religious attendance on treatment engagement were mediated by motivation to change. It was hypothesized that greater psychiatric distress, fewer family and social problems, and more frequent religious attendance would increase treatment engagement both directly and indirectly through the hypothesized increase in motivation to change. It was also hypothesized that these significant predictors would be more important, as demonstrated by better model fit among the variables, for female participants than male participants. One hundred seventy eight participants attending drug-free outpatient treatment and participating in a larger study called the STOP Project were included in this secondary analysis. Path analysis was used to test the model for the entire sample as well as separately for the 112 male and the 66 female participants. Results supported the fit of the hypothesized model. However, the hypothesis that motivation to change would act as a mediator in the model was not supported. The statistical significance of psychiatric distress, family and social problems, and religious attendance as predictors of treatment engagement was not supported, nor was there support for the link between these variables and motivation to change. Treatment site, a covariate in the model, predicted treatment engagement well and legal problems, also a covariate in the model, significantly predicted motivation for change in the model. The model fit did not differ significantly between males and females. These findings support the existing literature which highlights the importance of treatment program design, in particular how comprehensive and multifaceted the program is for addressing the various needs of treatment attendees. The findings further support the existing literature which highlights the role of legal coercion for motivating individuals to change drug use behaviors. The results are discussed in terms of both clinical and research significance.