Early childhood comprises several life stages, marked by developmental milestones. Here, we define early childhood as the period from birth to age eight, although we also recognize the importance of quality prenatal care in early childhood outcomes. Ours is a definition shared by many leading national and international organizations. We end with age eight because it reflects an important developmental milestone. Age eight corresponds to third grade, a critical year for mastery of the reading skills upon which further learning will build and a reliable predictor for future education success. Early childhood, which spans the period up to 8 years of age, is critical for cognitive, social, emotional, and physical development. During these years, a child’s newly developing brain is highly plastic and responsive to change as billions of integrated neural circuits are established through the interaction of genetics, environment, and experience. Optimal brain development requires a stimulating environment, adequate nutrients, and social interaction with attentive caregivers. Although ages zero to eight represent a clear developmental continuum, there are good reasons why funders and programs specialize in one stage. The needs of children and their families evolve and different organizations are positioned to play different roles at different stages. For example, infants and their parents may be more easily reached through the health system, while the prospects of older children may be more easily influenced through their elementary school. Ideally, investments across all stages would be sequenced and coordinated so that the child who benefits as an infant from one program moves seamlessly to environments that will continue to support her development.
Many of the programs we profile in this toolkit focus on “at-risk” children. An “at-risk” child is one who, given several factors related to his family situation and environment, is more likely than the average child to experience abnormal brain development, have difficulties succeeding in school and life, and in some instances is also more likely to engage in behaviors (such as smoking or taking drugs) that are detrimental to health.