The importance of adequate housing for the maintenance of health and well-being has long been a topic of scientific and public health policy discussion, but the links remain elusive. Here we explore the role of the residential environment in the etiology of illness (specifically asthma) and the persistence of socioeconomic health disparities. Housing conditions, shaped by social forces, affect exposure to physical and chemical "toxicants," thereby translating social adversities into individual illness and population health disparities. We discuss the mediating role of housing in determining health outcomes at multiple levels (social-structural, neighborhood, and individual family). To date, little attention has been paid by most environmental health scientists to the social-structural conditions underlying gross inequities in the distribution of toxic exposures, with even less attention to the processes whereby these social conditions may directly affect susceptibility to the toxic exposures themselves. This chapter goes beyond traditional medical and environmental science models to incorporate a range of social and physical determinants of environmental pollutions, illustrating how these conditions result in health and illness. We focus here on childhood asthma as an example of a serious public health problem that has been associated with low income, minority status, and characteristics of the home environment. We end the chapter with a discussion of the environmental justice movement and the role of housing as a potential agent of change and focus of interventions aimed to reduce the harmful effects of environmental pollutants.