Environmental health research must achieve an integration of understanding, reaching from physiological research on health effects of toxic agents to actions that people may take, individually and collaboratively, to reduce their risks. This article proposes an integrative model of environmental health, encompassing four broad domains and their interrelationships: physiological, vulnerability, epistemological, and health protection. If we wish to empower communities to make the tough decisions necessary to truly protect the well-being of their most vulnerable members, each domain must be attended to, and links between scientific knowledge and social processes must be understood.