The findings suggest that previous psychological treatments may have been effective in reducing levels of distorted perceptions/attitudes among sex offenders with an intellectual disability. There were significant differences in distorted perceptions/attitudes related to sexual offending between those sex offenders who had received treatment and those who had not been treated. The non-treatment group scored significantly higher on the Rape, Exhibitionism, Homosexual Assault, Pedophilia, Stalking, and Sexual Harassment sections of the Questionnaire on Attitudes Consistent with Sexual Offending (QACSO) compared with the sex offender treatment group and nonoffenders. There was no significant difference between the treatment group and the nonoffender group on any of the sections of the QACSO or the total QACSO score. There was no difference between the three groups regarding locus of control. All participants endorsed an "external" locus of control, i.e., they perceived that events controlled them significantly more than they controlled events. Previous studies have found that an external locus of control is linked with poorer treatment outcomes for sex offenders without an intellectual disability. The authors discuss three possible explanations for how locus of control relates to sexual offending by individuals with intellectual disabilities. All participants completed the (QACSO) and the Adult Nowicki-Strickland Internal-External Scale. The latter measures perceptions of locus of control. 3 tables and 27 references