The proportion of sixteen-year olds in Britain who stay on at school is low by OECD standards. This paper examines the probability of completing education at the minimum legal age using micro data on individuals. Parameter estimates of a reduced-form logit model of the leaving probability are obtained for both boys and girls. The rich data set used allows the separate effects of family, school, and ability to be assessed. Family background, in the form of class and parental education, is shown to have a large effect even when ability and school type are controlled for. Copyright 1989 by The London School of Economics and Political Science.