In 1791 Condorcet passionately defended “common education for both sexes in mixed schools” as a democratic measure - but his words fell on deaf ears. Nine decades later, the Republicans opted for single-sex schools when they created state secondary education for girls. Despite the spread of co-education in the United States and elsewhere, mixed-sex education remained a Utopia in late 19th century France. It was not until 1976 that mixed-sex education became the norm at all levels of education and was no longer the subject of debate and controversy. However, we now know, as Geneviève Fraisse wrote, that “mixed-sex education is necessary, but not sufficient, to break down persistent inequalities”. The history of this pedagogical revolution, its opponents and defenders, its successes and failures, had not yet been fully recorded. In this volume, historians and sociologists present us with analyses from the distant and recent past as well as comparisons with other European countries where mixed-sex education is the subject of debate. Whereas the issue of mixed-sex education has become a subject of public debate, its history and challenges deserve mention as they show the extent to which putting boys and girls together has never been purely a question of gender management. It affects society as a whole.