Early cognitive and socio-emotional skills play a crucial role in shaping academic achievement and overall well-being. Consequently, socioeconomic disparities in the development of these skills raise significant concerns. These disparities are evident even before preschool . Participation in high-quality early childhood education and care (ECEC) before preschool is associated with improved cognitive and socio-emotional abilities, particularly so among children from low socioeconomic status (SES) backgrounds. Additionally, access to ECEC facilitates women’s employment, leading to increased family income. ECEC therefore has the potential to reduce early inequalities in child development. However, in most OECD countries, there is a socio-economic gap in ECEC enrollment, meaning that families with a low-socioeconomic status (low-SES) attend these structures the least. This gap is particularly large in France, where there is 65 a percentage points difference in attendance between the third and first-income tertiles in 2014, despite ECEC being heavily subsidized for low-SES families and its costs being means-tested. In 2018, only 19% of families below the poverty had access to ECEC. This unequal attendance can thus further exacerbate inequalities in child development and school success. If policymakers want ECEC to act as a means of reducing inequalities, they must ensure that those with the highest potential benefits can easily access it. Yet, very little is known about the determinants of the ECEC enrollment gap.