By tracking the records of individual looked after children from GCSE back through Key Stages 3, 2 and 1, Angela O'Sullivan and Rob Westerman were able to show a steady widening of the gap between their attainment and that of children not in care. Despite weaknesses in local authority data, the evidence is clear that the frequency and timing of placement and school moves play a crucial part in preventing children in care from achieving the levels predicted by their earlier Key Stage grades. The article concludes with practical suggestions for change.