The co-working relationship between general practitioners and local mental health services lies at the heart of the success of recent changes in mental health care. These changes have seen large-scale deinstitutionalisation, a shift to primary and community care, and a government policy of prevention and partnerships. This article outlines a liaison project developed jointly by the South-East New South Wales Division of General Practice and the Southern Area Mental Health Service to address these issues. We describe the development of a protocol of basic standards which were practical, pragmatic and possible and, when fully established, would be the foundation of effective, efficient and efficacious shared care in mental health.