Developmental scientists have long been interested in how the environment influences children's development. However, with few exceptions, they have not researched how exposure to contaminants in the physical environment affects developmental processes. Children are uniquely at risk for exposure to contaminants because they drink more, eat more, and breathe more air than adults as a proportion of their body weight. In this article, we provide an ecosystems perspective to illustrate how contextsâ€”from the prenatal environment and neighborhood-level exposure to laws and policiesâ€”contribute to children's exposure to contaminants. We also discuss four mechanisms that account for how and when exposure to contaminants affects children, and we provide examples to spur research on these mechanisms. We conclude with recommendations to foster integrative science where developmental science interacts with environmental health and toxicology.