In most OECD countries, subsidised childcare is a key instrument to support maternal employment. Using a large reform implemented in Luxembourg in 2009, I study the effect of expanding access to subsidised childcare on childcare and employment decisions of women in a context where childcare is universal and heavily subsidised, but bound by capacity constraints. The identification relies on temporal variation across child age groups. The results show that, in response to the reform, the employment rate of mothers increased by 4-7 percentage points and their hours of work by around 3 hours per week. Studying heterogeneous effects reveals a differential impact of the reform for more vulnerable mothers. Parents whose youngest child is under the age of 3 are found to use more daycare services, for longer hours, while the use of informal care remains unchanged. These results suggest that there is no crowding out effect of the new policy.