Prosperity in the world today depends on societies' nurturing of young children. Quality care (stimulation, health, and nutrition) during ages 0 - 5 has a decisive and long-lasting impact on a person's development, ability to learn, and capacity to regulate emotions. Cognitive and noncognitive (social and emotional) skills, set early in life, determine later success. New research in neurobiology and the behavioral and social sciences is converging to enhance this understanding of early child development. Recently, researchers noted epigenetic effects in brain development - that is, the interaction of environment (early experiences) with genetics to shape brain structure and function - that with proper nurturing would enable people to have competence to create prosperous, sustainable, tolerant, nonviolent, and democratic communities. The World Bank recently hosted a symposium on the priority of early child development for economic growth and equity. The participants urged application of population - based tools and measures to assess the outcomes of children's early years and children's readiness for school. This approach, which shifts the focus from measures of disease, dysfunction, and mortality, is already yielding essential data for designing intervention programs, identifying children at risk, and leveraging policy and investment - to improve the possibilities for all children globally.