This article analyses the impact of a value-added performance indicator (PI) on the rankings of secondary schools in the English league tables. School rankings are seen to be very sensitive to the type of PI employed, and the new value-added PI is likely to result in significant movements up and down the rankings. There is still scope for schools to try and game the system in order to improve their league table position. Value-added PIs reduce the incentives for schools to select their pupils, but the version currently employed in England may create an incentive for schools to distort effort away from those pupils at the top end of the distribution. The value-added PI is shown to provide a more accurate measure of school performance. However, in order for parents to be effective drivers for improvement in the education market, it may also be necessary for the government to measure the impact of differential value-added across different student types.