Differences in offense history, brain functioning, and psychological functioning of rape (n = 45) and molest offenders (n = 15) who were receiving psychiatric treatment while in prison were evaluated. Significant differences were found in each of these domains. Rape offenders were more likely to have histories of high violence offenses other than sexual offense, including murder, serious juvenile offenses, and both juvenile and adult sexual offenses. Rape offenders were more likely to show lower intellectual functioning and diffuse brain dysfunction associated predominantly with temporal and prefrontal brain cortices. Rape offenders were also more likely to display psychological functioning associated with illogical thinking and disordered attachment but less immature self-focus and fewer feelings of alienation than demonstrated by molest offenders. Implications for treatment and social policy for sexual offenders are suggested. Logistic regression demonstrated that these neuropsychological measures resulted in 71.7% accurate prediction and Rorschach measures resulted in 79.2% accurate prediction in differentiating rape from molest offenders. Implications for theoretical understanding of sexual offending are discussed.