Professor Harris is highly regarded for his research into the prevention and management of chronic disease in general practice and community health services, vulnerable population (including Aboriginal and refugee health) and access to primary health care. This has given rise to over 300 publications in the national and international peer review research literature and is highly cited. He leads and participates in international collaborative research with researchers in the US, Canada and the UK. His research has been highly influential with his profession including the development of clinical management guidelines and helped inform policy of the Commonwealth and NSW Governments.