Answer: 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 educational success.