Hence there is a need to develop indicators of population mental health that also reflect mild-to-moderate mental illness. A number of factors are responsible for this lag including the complex nature of mental health problems, high rates of co-morbidity and lack of agreement on suitable measures. Stakeholder - in particular clinicians, patients and families - involvement and the integration of quality and outcome measurement into key processes of care are integral to ensuring mental health is at the forefront of high-quality services that are efficient and deliver value for money. To understand mental health system performance at an international level, better measures of the quality and outcomes of mental health care are needed.