His research focuses on the prevention and treatment of mental health problems in people with autism or intellectual disabilities across the lifespan. He conducts studies into how people with developmental disabilities access mental health care in Ontario, and is interested in their health service needs, their emergency service use, and their experiences of psychiatric crisis. Dr. Weiss holds the CIHR Chair in Autism Spectrum Disorders Treatment and Care Research, as well as operating funds from the Canadian Institutes of Health Research and Social Sciences and Humanities Research Council.