A great deal of criminological and psychological research has focused on high-risk violent offenders. Two criminogenic factors have been identified that may account for the violent behavior of these high-risk offenders: immature sociomoral reasoning capacity and criminal thinking in the form of pro-offending sentiments. These two variables have been the center of an ongoing debate about whether it is how offenders reason or whether it is their pro-offending attitudes that allow for engagement in criminal activities. In order to test the hypothesis that immature-level offenders would endorse stronger pro-criminal sentiments than mature-level offenders and mature-level nonoffenders, the authors recruited an experimental group of 99 male and female high-risk offenders incarcerated in 4 West Australian metropolitan prisons and a control group of 101 male and female nonoffender university students. Both groups of participants completed the Sociomoral Reflection Measure-Short Form and the Criminal Sentiments Scale. Results generally support the hypothesis. Mature-level nonoffenders espoused stronger positive attitudes about the justice system, were less willing to neutralize law breaking behaviors, and had lower identification with criminal peers than both offender groups (mature and immature offenders). However, surprisingly the results revealed that the level of sociomoral development for the two offender groups did not impact their negative attitudes toward the justice system, their high tolerance for law breaking behavior, and their identification with criminal peers. These findings indicate that criminal sentiments endure even as sociomoral development continues; pro-offending attitudes become embedded within the belief system even as an individual develops mature levels of sociomoral reasoning. Results have implications for interventions that target the sociomoral development of offenders. If the aim of the intervention is to increase moral reasoning based on the assumption that higher moral reasoning will lower criminal behavior, the intervention may be misplaced. Table, notes, references