Children’s health is the foundation for health throughout life, and measures of child health are important indicators of our nation’s overall state of health. This chartbook focuses on the health of children to explore whether we are reaching our full health potential as a nation and in every state. Considering the differences between ‘what is’ (current overall levels of child health) and ‘what is attainable’ (the levels of health that would be achieved if all children were as healthy as children in the most favorable social and economic conditions), the new state-by-state evidence presented here reveals substantial unrealized health potential.