Assessment and treatment of adults with learning disabilities who commit sexual offences presents a number of challenges. Much of the professional forensic and psychiatric literature on work with this group concentrates on the development of interventions based on theoretical models of sexual offending originating from the mainstream criminal justice system and have often been adapted and applied to people with learning disabilities. Currently, there is very little evidence to demonstrate the effectiveness or validity of the adaptation and application of mainstream models to this population. The efficacy of such adapted models used to describe sexual offending in people with learning disabilities clearly has an impact of any intervention informed by them. In particular, some researchers suggest that key factors such as cognitive distortions are evident in sexual offenders with learning disabilities; there is, however, no research relating to the prevalence of these or other key factors within the general population of people with learning disabilities. The present literature review highlights some of the clinical issues with a particular focus on the assessment of deviant sexual interest. Specifically, the literature is confused with inconsistencies relating to the definition of the group, the extent and nature of offending and a lack of standardized methodology for assessment and comparison. Consideration is given to the particular needs of this group and the implications for research and treatment.