The RSTI-SR was recently designed to facilitate juvenile evaluations by tapping 3 pertinent juvenile psycho-legal variables including risk, developmental maturity, and treatment amenability. The present study examined the factor structure and construct validity of the RSTI-SR with 190 adolescent offenders (Mage = 15.6) who completed the RSTI-SR and a short battery of theoretically relevant psychological measures. The findings from the current study demonstrated that the proposed 3-factor model for the RSTI produced good fit to the data. Factorial invariance testing further found the model to be tenable for both male and female young offenders. Moreover, preliminary construct validity was established for the RSTI-SR factors through significant associations with relevant external variables including psychopathy, general personality (e.g., extraversion, agreeableness), coping, openness, and well-being. Initial results show the RSTI-SR to be a promising new measure for assessing the functioning of young offenders.