Prison-based drug treatment has shown promise as an effective way to reduce the rate of drug use and recidivism for drug-involved offenders. Research has shown that there are several factors that lead to an individual becoming motivated, ready, and engaged in treatment. Factors such as familial obligations, legal sanctions, and individual characteristics have been shown to impede or facilitate an individual's successful rehabilitation. Although previous literature attempts to elucidate the personal factors that can contribute to an individual's success in a prison-based drug treatment program, one gap in the literature is the failure to examine the effect that inmate and programmatic characteristics can have on an individual's engagement in the treatment program. The individual characteristics include an inmate's personality, as well as external pressures on the inmate to participate in the program, while programmatic characteristics include program structure and peer rapport. Particularly rare in the literature is the use of qualitative methodology to explain inmate and programmatic characteristics and their relationship to the therapeutic engagement of inmates in prison-based therapeutic community. What differentiates this study from others in the drug treatment literature is that it qualitatively examines the factors that enhance or impede therapeutic engagement (the involvement in and commitment to drug treatment) of inmates in a prison-based drug treatment program. Specifically, therapeutic engagement is shown to be a product of external coercion, including familial and legal factors; internal motivation and treatment readiness; and program factors, including group meetings, activities, work assignments, authority structure, and counselor/inmate rapport. In order to study the effects of these characteristics on therapeutic engagement, thirty inmates at the State Correctional Institution at Chester (PA) were interviewed three times over a six-month period regarding the therapeutic community in which they had participated. Impressions of the inmate were noted during each interview, and each inmate's treatment file was reviewed at three distinct points of the treatment process. Results suggest that the unique characteristics of an inmate may have greater influence than program characteristics on the inmates' involvement and commitment to engage in the drug treatment program. (PsycINFO Database Record (c) 2019 APA, all rights reserved)