Background: This study compares outpatients with intellectual disability (ID) receiving specialised services to outpatients with ID receiving general services in Ontario's tertiary mental healthcare system in terms of demographics, symptom profile, strengths and resources, and clinical service needs. Methods: A secondary analysis of Colorado Client Assessment Record data collected from all tertiary psychiatric hospitals in the province was completed for a stratified random sample of 246 outpatients identified as having ID, from both specialised and general programmes. Results: Individuals with ID in specialised programmes differed from patients with ID in general programmes with regard to demographics, diagnostic profile, symptom presentation and recommended level of care. Conclusions: Further research is required to determine why individuals access some services over others and to evaluate whether specialised services are more appropriate for certain subgroups with ID than others.