There has been a long running debate between the advocates and opponents of coeducation in Britain. Each side has made claims about its academic, social and psychological consequences for boys and girls. We shall investigate these claims empirically, using material gathered as part of two large scale longitudinal studies. The size of the samples will enable us to control for a number of variables which are associated with single and mixed-sex schooling. For intance we can look at pupils' school performance in single and mixed-sex schools while controlling for whether schools are also selective or comprehensive, and state or private. The fact that the cohort studies contain information on the individuals from birth to age 30 and 40 will also allow us to test some of the supposed longer term consequences of single and mixed-sex schooling, for instance whether women from single-sex schools make more unconventional choices of occupation, and whether men from coeducational schools have more egalitarian attitudes towards the gendered division of work in the home.