Studies show that companies with women in top roles earn higher returns, share prices, and organizational-health scores than those with all-male leadership. Yet despite mounting evidence that executive diversity is associated with better performance, the glass ceiling has stayed mostly intact: worldwide, women still hold less than a quarter of senior management positions, and solutions such as boardroom quotas have so far failed to change the overall number of female executives. While business leaders debate measures to address gender inequality, they might consider its relationship to that all-important marketplace metric: economic growth.