Prenatal and childhood environmental exposures are an underrecognized primary cause of intellectual and other developmental disabilities. In addition, individuals with established disabilities are vulnerable to further harm from subsequent environmental exposures. In individuals with communicative impairment or limited ability to independently escape from hazards, these subsequent exposures, too, may occur undetected or untreated. This article introduces the subject of environmental health and developmental disabilities throughout the life span. In particular, we focus on ways that families, communities, and health professionals can prevent both primary and secondary disabilities through better awareness of common environmental health issues.