Evaluations of the impact of universal preschool on maternal employment find higher impacts in countries with lower initial levels of female employment, use of private childcare, and welfare benefits. Where policies have encouraged more mothers to work, impacts have often been concentrated among low-income or single mothers whose youngest child is eligible for preschool and have persisted after the child has left preschool. The varied impacts of these policies suggest that subsidizing preschool only for mothers for whom affordability is the main barrier to work may be a more cost-effective way to increase maternal labor supply.