In this chapter, we critically review the health effects of environmental stressors. To keep the scope of this discussion manageable, we limit our domain in several ways. First, although we will consider the health effects of crowding and air pollution, emphasis will be placed on the noise literature. Second, because possible effects on the cardiovascular system have been among the most widely studied health consequences (particularly with respect to noise), these effects will receive the most attention here. Third, the review will be selective, rather than exhaustive, emphasizing major trends in the literature. Intensive reviews of the particular health effects of individual stressors such as noise, crowding, air pollution, and heat can be found in other sources (Cohen & Weinstein, 1982; Evans, 1982; Evans & Cohen, in press; USEPA, 1980, 1981).