Results indicate that inmates in female treatment programs report more psychosocial dysfunction, less criminal thinking, and higher engagement than in male facilities, and demonstrate more negative relationship between psychosocial variables and treatment engagement compared to males in programs. By assessing factors that might influence treatment engagement, such as psychosocial issues and criminal thinking early in the treatment process, programs might be able to target treatment interventions designed to specifically address these problems in an effort to enhance the retention rates, treatment experience, and treatment outcomes for their clients; clients who do not engage in treatment are less likely to complete treatment and less likely to have positive treatment outcomes. This study focused on gaps in the current research and had three study objectives: to examine differences between male and female programs in treatment engagement, psychosocial functioning, and criminal thinking; to examine program based gender as a moderator of the relationship between treatment engagement and psychosocial functioning; and to examine gender as a moderator of the relationship between treatment engagement and criminal thinking. The sample consisted of 2,774 substance abusers enrolled in 20 prison-based treatments programs in 5 different States. Participants were 56 percent non-White, with a mean age of 34 years and a mean length of treatment of 141 days. The study was limited in several ways: participants were not randomly selected but were part of a targeted drug treatment program eligible for study, data were self-reported, and only two primary factors on treatment engagement were examined. Additional factors such as individual differences and motivation for treatment should be considered for future analyses. Tables, references