Studies of community-based substance use treatment show that motivation for treatment is critical for clients becoming therapeutically engaged. Little research, however, has been conducted on therapeutic engagement in corrections-based substance use treatment. The current study examines the association between internal treatment motivation and therapeutic engagement for a sample of 220 male substance-using offenders enrolled in a corrections-based treatment program. Findings showed that problem recognition and desire for help were associated with cognitive indicators of therapeutic engagement, specifically confidence in and commitment to treatment. Increased focus on internal motivation for treatment may lead to more effective treatment for substance-using offenders. Pretreatment motivational interventions therefore are recommended for substance-using offenders with low internal motivation for treatment.