If we are to be able to reflect the cost implications of changes in the nature, quality and productivity of long-term care interventions in future projections, we need an approach to measurement that reflects the value and quality of care. This paper describes a theoretically based but pragmatic approach to identifying the welfare gain from government expenditure on social care and illustrates an application in projecting the costs of long-term care used in the Wanless review of future needs of social care for older people in England.