During and following a disaster caused by a natural event, human populations are thought to be at greater risk of psychological morbidity and mortality directly attributable to increased, disaster-induced stress. Drawing both on the research of others and that conducted at the Center for Public Health and Disaster Relief of the University of California-Los Angeles (UCLA) following California earthquakes, this paper examines the extent to which research evidence supports these assumptions. Following a brief history of disaster research in the United States, the response of persons at the time of an earthquake was examined with particular attention to psychological morbidity; the number of deaths that can be attributed to cardiovascular events and suicides; and the extent to which and by whom, health services are used following an earthquake. The implications of research findings for practitioners in the field are discussed.