Static, dynamic, and protective factors have been identified as three focal domains significantly related to offender recidivism. However, few measures include comprehensive and inclusive assessment of these variables. The Inventory of Offender Risk, Needs, and Strengths (IORNS) was developed to fill a void in the assessment of risk and needs for offenders. The current study examines the reliability and initial validity of the IORNS in a sample of pre-release offenders assessed for risk and treatment need. Results indicate moderate to high levels of internal consistency and identical IORNS scale results across race, and that the IORNS indexes, scales, and subscales display good convergent validity with self-report and interview measures of static risk, dynamic risk, antisocial behavior, psychopathy, personality pathology, substance abuse, depression, and anxiety. Initial predictive validity examination of the IORNS indicates that several of the indexes, scales, and subscales were able to differentiate offenders who were sent back to prison for half-way house rule violations from those who did not violate rules.