This article provides a brief overview of the field of disaster research, summarizing what is known at present about the prevalence of disasters, the range of stressors and outcomes experienced, and sample-, event-, and individual-level Excluding droughts and war, there are almost 500 incidents annually, worldwide, that meet the definition of a disaster as given by the Red Cross: an event that involves 10 or more deaths, affects 100 or more people, or leads to an appeal to them for assistance. 1 Across these events, 50,000 people die, an additional 74,000 are seriously injured, 5 million are displaced from their homes, and over 80 million are affected in some way. The causes of disasters are many, including natural forces, such as floods, hurricanes, and earthquakes; failures of technology, such as nuclear, industrial, and transportation accidents; and mass violence, such as shooting sprees and peacetime terrorist attacks. Regardless of their cause, disasters damage local infrastructures and strain the ability of local systems to meet the population's basic needs. For the survivors, disasters may engender an array of stressors, including threat to one's life and physical integrity, exposure to the dead and dying, bereavement, profound loss, social and community disruption, and ongoing hardship. As a result of both the high prevalence and high stressfulness of disasters, the question of whether they have an impact on mental health has been of interest for decades, and substantial literature has developed that identifies and explains these effects.Norris and colleagues 2,3 recently attempted to provide a synthesis of this vast body of literature. The review was restricted to quantitative studies published in English between 1981 and 2001 and selected from various databases using the search term disaster(s). That analysis encompassed 160 distinct samples of disaster victims composed of over 60,000 individuals who experienced 102 different events. The range of consequences experienced by these disaster survivors was broad, including various psychological problems, such as depression, anxiety, and (most notably) posttraumatic stress disorder (PTSD); physical health problems, such as sleepThe author is with the