Why do married women work less in the UK than in France?

Compared to their French counterparts, British married women choose fewer working hours but similar employment rates. This is driven mostly by the labour supply choices of those with young children. To understand why, I estimate a structural labour supply model and simulate counterfactual hours distributions. Differences in non-work income and childcare prices together explain about two-thirds of the observed labour supply gap for mothers of young children. Most prime-aged British married women also face significantly lower taxes compared to their France counterparts though they do not work significantly more aggregate hours. I estimate strong preferences differences across the Channel.