Families with four or more children account for less than 5 per cent of all families, but more than 20 per cent of poor children. This research was commissioned by the Department for Work and Pensions (DWP) to contribute to its policies to eliminate child poverty. The aim was to investigate whether it is family size itself that explains the relatively weaker economic position of large families, or whether there are other factors associated with having many children which are also associated with a high risk of poverty.