The current study examined the relationship between need for cognition (i.e., cognitive motivation or "will") and educational experience (i.e., cognitive ability or "skill") to perceived improvements during treatment of probationers receiving residential treatment within the criminal justice system. Probationers were randomly assigned to either receive motivational activities developed by the authors (the "enhanced" condition), or treatment as usual (but with access to general reading materials in lieu of the motivational activities). Need for cognition and educational experience were assessed and used as blocking variables, and ratings of progress were assessed midway and toward the end of treatment. The results indicate that both need for cognition and educational experience are important predictors of improvement during treatment, and that the motivational activities developed by the authors were particularly valuable for clients with lower levels of need for cognition.