Performance measurement in social care is now considerably more advanced than previously. However, measurement is criticised on the basis of its presentation as neutral when, in the UK, it is part of the government's regulatory regime. However, measurement is important, especially when alternative methods may bring about different rankings of authorities to those endorsed by the recent system. This paper explores this issue through analyses of cost efficiency in English social services authorities. It concludes that the picture of authorities' performance depends on the method chosen which, it is argued, should stem from the stated aims of performance monitoring.