This article traces the evolution of sexual and social inequality at school since the beginning of the 20th century, enlightened by the social and economic context. It is based on data Formation-Qualification Professionnelle survey, collected by the INSEE. The history of boys' and girls' education shows how the girls caught up with the boys, followed by a reversal of the situation to the profit of girls in gaining access to the different levels of the 1st and 2nd cycles in secondary education, while respecting relatively speaking, the inequality between sexes depending on the branch and field of study. The reversal of sexual inequality is in contrast to a more discrete reduction of social inequality which remains important throughout the whole period. The hierarchy of social inequalities is little affected and remains similar for both sexes ; children of senior executives stand out clearly from the others. In the working-classes it took longer for girls to catch up with boys, but today they have a strong advance. Girls from farming and self-employment backgrounds are the first to benefit from this evolution. The theory of a dual handicap due to sex and class, upheld in several works, is therefore only confirmed for the older groups.