This chapter surveys recent literature on the drivers of mothers’ labour supply in OECD countries. We present a number of facts on the variations across time and across countries of family composition and mothers’ employment. We aim to answer key questions on their decision to return to work after childbirth: How is the decision taken within the household? What are the contemporaneous and longer term determinants of this decision? What other lifecycle choices are interrelated with the labour supply choice? How do social norms and policy influence this decision? What role is there for policy to play in households’ decision regarding mothers’ participation in the labour force? We aim to summarise the main results from recent research on these questions. We will see that there are large variations in the policy choices made in different countries, which may reflect both the difficulty of designing an optimal mix of policies and the diversity of societies’ perceptions of women combining motherhood and career.