Results indicated that the main differences and similarities between the perceptions and experiences of staff and participants involved in a prison-based substance abuse treatment program were in the areas of participant motivation, staff-participant communication, race, institutional support, and counselor contacts. Staff members and participants generally agreed that the main motivation for prisoner participation in treatment was for early parole opportunities. It was also generally agreed that staff-participant relationships were positive despite some communication difficulties between staff and participants, which were identified as being caused by racial differences and the prison environment. Staff identified the main challenges of the substance abuse treatment program as a lack of institutional support, racial divides, and understaffing. Participants, on the other hand, identified the main challenges as a lack of counselor understanding for participants and limited opportunities for individual counseling. The findings suggest that the number and intensity of staff-participant counseling contacts should increase and staff should be aware of the strains placed on the staff-participant relationship by the prison environment. Clinical implications of the findings suggest that a mutually supportive and therapeutic environment for substance abuse treatment should be developed and maintained. Data were drawn from in-depth interviews over a 4-year period between 1998 and 2001 with 2 administrators, 5 counselors, and 18 participants of a prison-based substance abuse treatment program at the Kentucky State Reformatory. Interviews were transcribed and coded using Lofland and Lofland’s (1995) qualitative data analysis techniques involving both an “initial” and then a “focused” reading of emerging themes. Follow-up studies should consider gathering qualitative data to provide in-depth insights into perceptions of substance abuse treatment programs. References, notes, appendix