Objective: The authors measured the total expenditures for two key sources of social support in Alberta in 2005 for persons with severe and persistent mental illness and compared these expenditures with the total mental health expenditures. Methods: Social services and assistance benefit data were from the federal government's Canada Pension Plan-Disability Benefits and from Alberta Services' Assured Income for the Severely Handicapped for beneficiaries with psychiatric diagnoses. These benefits were compared with the total public mental health expenditures in Alberta for budget year 2005—2006. Results: A total of 7,456 adults with certified mental illness conditions received federal disability benefits, and 17,138 received provincial disability and medical benefits. The total for social support (income) benefits was $207 million Canadian compared with $405 million Canadian spent by the provincial government for mental health services for adults under age 65. Conclusions: Social assistance forms a substantial portion of Canadian federal and provincial government support for persons with mental illness. Whenever a government-payer perspective is taken, these costs should be factored into the analysis. (Psychiatric Services 60:686—688, 2009)Abstract Teaser