Adults with severe mental illness have higher rates of many diseases and a shorter life expectancy than the general population, although the situation in New Zealand has not been examined. Factors implicated in this disparity include individual factors such as smoking rates and medication side effects, social factors such as poverty and unemployment, and service factors such as access to appropriate and effective general health services. This research will investigate the role of health services in mortality differences between those with severe mental illness and the general population, focusing on the example of cancer. The project will use routine data sources to establish the burden of cancer for users of mental health services, and to investigate the quality of cancer care provided to this group. This will be supplemented with data collected from interviews with service users and clinicians to examine the possible causes of any differences.