One of the specificities of French higher education is that there is no single higher education system but two compartmentalised and hierarchical higher education systems comprising (1) universities and (2) "grande école" higher education institutions. Competing for a place in the latter requires that students have succeeded in "classe préparatoire" studies at the undergraduate level (an intensive foundation degree). While access to university is open to all students, access to "classe préparatoire" is very selective and remains the source of many inequalities. Thus, in 2018, only 7% of students studying in "classe préparatoire" programmes had a working-class father, compared with 50% whose father was a manager, and less than 43% were women, 30% of whom were in the science stream (RERS, 2018). Numerous reforms have been implemented over the past thirty years to mitigate inequalities associated with gender, social and cultural status, as well as geographical location. This study analysed the impact of reforms on the evolution of inequalities. With focus on social and gender inequalities, I use a dual approach to analyse questions pertaining to access and the impact of reforms; specifically, (1) a cliometric approach, based on a quantitative historical analysis of long time series, and (2) a microeconomic approach that relies on individual series. I show that despite measures aimed at opening access to students of different gender and social backgrounds, the "grandes écoles" higher education institutions remain a relatively compartmentalised system that perpetuates the reproduction of social and gender inequalities.