Expanding women’s economic opportunities benefits both women and society. Women’s choices widen and societies gain from the contribution that women’s income makes to economic growth and family wellbeing. These benefits are increasingly well-understood, but much less is known regarding the most effective interventions to empower women economically. The call to find out what works is long overdue. Gender gaps in economic performance are pervasive and persistent — women earn less than men across countries and occupations, and gender gaps are especially salient in poor countries. A wide range of policies and programs — from long-term investments in health and education to short-term training programs and ‘just-in-time’ information on markets — can potentially help close these gender gaps and bolster women’s economic advancement.