The proportion of children suffering from chronic illnesses--such as asthma and obesity, which have significant environmental components--is increasing. Chronic disease states previously seen only in adulthood are emerging during childhood, and health inequalities by social class are increasing. Advocacy to ensure environmental health and to protect from the biological embedding of toxic stress has become a fundamental part of pediatrics. We have presented the rationale for addressing environmental and social determinants of children's health, the epidemiology of issues facing children's health, recent innovations in pediatric medical education that have incorporated public health principles, and policy opportunities that have arisen with the passage of the 2010 Patient Protection and Affordable Care Act.