The origins of adult health and well-being stem from genetic-environmental interactions that begin in the first 1000 days (conception through 24 months). Children with adequate nutrition and opportunities for early learning and responsive caregiving have the best chances of thriving. This paper focuses on associations among nutrition, environment and brain development. The first section examines relations among child development, poverty and nutritional deprivation (stunting). The second section examines how prenatal maternal nutrition relates to children’s brain development and functioning. The third section examines associations among specific nutritional deficiencies in early life and early brain development. The final section examines the evidence on early interventions designed to overcome the nutritional and environmental threats and to promote early child development.