In an effort to reduce first-time sexual offending, this study focuses on the development of a risk assessment tool, the Minnesota Sexual Criminal Offending Risk Estimate (MnSCORE), designed for prisoners without any prior sexual offending history. Logistic regression modeling was used to develop the MnSCORE on a sample of 9,064 male offenders released from Minnesota prisons between 2003 and 2006. Bootstrap resampling was used to not only refine the selection of predictors but also internally validate the model. With an optimism-corrected area under the curve (AUC) of 0.763, the results showed the MnSCORE has moderately high predictive discrimination. Because the risk of first-time sexual offending was significantly lower for offenders who completed prison-based chemical dependency (CD) treatment, it is anticipated the MnSCORE may best be used as a trailer assessment to help better prioritize prisoners for CD treatmentboth in prison and in the community following release. Abstract published by arrangement with Sage Journals.