Children's development of cognitive, affective, and behavioral capacities is best promoted when the contexts that surround them are strong and healthy. Children are embedded in families, who are, in turn, embedded in communities. Policies or programs that strengthen families and communities by addressing the social determinants of health also promote children's healthy development, and ultimately national prosperity. We provide examples of housing, education, and income policies that address the social determinants of health. We suggest that their potency is augmented when they also strengthen the collective efficacy of families and communities, thus laying the foundation for children's long-term, healthy development. We urge a concerted focus on these broad social policies as a key component of any children's health policy.