A total of 89 adult males incarcerated in a maximum-security correctional facility of the Nebraska Department of Corrections participated in the study. Of the total sample, 69 were sexual offenders currently involved in a cognitive-behavioral sexual offender treatment program. Forty-four had been convicted of actual or attempted sexual assault on a child or had admitted to having sexual contact with a child; 28 had been convicted of actual or attempted sexual assault against an adult female (rapist group). Two lists of cognitive distortions derived from clinical and research experiences in the assessment and treatment of child molesters and rapists were compiled to form the original 44-item MOLEST Scale and the original 36-item RAPE Scales. The scales, along with the Multiphasic Sex Inventory, were administered to each of the convicted sexual offenders. Results show that the MOLEST and RAPE Scales are promising clinical and research measures that show strong internal consistency and reliability, convergent and discriminative validity, freedom from a socially desirable response bias, and utility in assessing the efficacy of a cognitive restructuring treatment component. Sexual offenders' cognitive distortions as assessed by the MOLEST and RAPE Scales were found to be related to the number of victims and duration of sexually assaultive behavior. 3 tables, 2 figures, 35 references, and appended scales