This article examines the association of iron deficiency (ID) and iron deficiency anemia (IDA) with children's development and behavior, with the goal of providing recommendations to prevent the developmental loss associated with these conditions. Children's risk for ID and IDA is particularly high during the second 6 months of life when prenatal stores are depleted. Longitudinal studies from infancy through adolescence and early adulthood suggest that socioemotional development is uniquely vulnerable to ID and IDA, perhaps being associated with shared neural pathways, and the effects of early iron deficiencies may be irreversible. In addition to direct effects on brain function, ID and IDA may also affect child development indirectly through non‐responsive mother‐child interactions. Maternal ID is a global problem that may contribute to high rates of maternal depression and non‐responsive caregiving. Intervention trials illustrate that children benefit from both nutritional intervention and early learning interventions that promote responsive mother‐child interactions. Recommendations to reduce the developmental loss associated with ID and IDA are to reduce the incidence of these conditions by efforts to prevent premature birth, delay cord clamping, ensure adequate maternal iron status, provide iron‐rich complementary foods, and ensure access to postnatal interventions that promote responsive mother‐infant interaction patterns and early learning opportunities for infants.