This article synthesizes knowledge about opportunities to improve the state of early child development globally. Research confirms a strong association between child survival and child development. The evidence and its interpretation are derived primarily from three sources: (a) peer-reviewed scientific literature, (b) reports from governments, international agencies, and civil society groups, and (c) a knowledge network of experts in ECD. The principal insight of our knowledge synthesis is that nurturant qualities of the environments where children grow, live, and learn—parents, caregivers, family, and community—will have the most significant impact on their development. We propose ways in which government and civil society actors, from local to international, can provide equitable access to strong nurturant environments for all children globally.