Social science research on disasters began in the early twentieth century with the publication of Samuel Henry Prince's sociology doctoral dissertation on the 1917 Halifax explosion (Prince 1920). However, disaster research did not begin to coalesce as a field until pioneering research was carried out by the National Academy of Sciences and the National Opinion Research Center in the early 1950s, as research teams were sent into the field to collect data on individual, group, and organizational responses to disasters (see Fritz and Marks 1954). The Disaster Research Center, established in 1963 at the Ohio State University and now located at the University of Delaware, continued the practice of conducting "quick-response" studies following major disasters, with an emphasis on organizational and community response. Over subsequent decades, other research centers were established both nationally and internationally. The terrorist attacks of September 11, 2001 generated additional interest in disaster research, as questions were raised concerning a range of topics, including behavioral, psychological, and social-psychological responses to terrorism. Classic sociological research on disasters emphasized the pro-social and adaptive dimensions of disaster-related behavior. Studies consistently documented such patterns as widespread helping behavior among community residents, the emergence of new groups focusing on victim and community needs, increases in social cohesion, the convergence of volunteers and material resources into disaster areas, and the suspension of community conflicts as community residents and public and private-sector organizations put aside their pre-disaster agendas in the interest of overcoming disaster-induced challenges. Disasters were framed in the literature as "consensus" crises and contrasted with "conflict" crises such as riots. Outcomes following disasters include the emergence of "therapeutic communities" that support victims and maintain high community morale. Therapeutic communities help to cushion the negative psychological consequences of disasters, and as a result, negative psycho-social reactions tend to be short-lived following disasters (see Fritz 1961; Barton 1969; Dynes 1970; Stallings and Quarantelli 1985; Drabek 1986). Ongoing research on disasters provides additional support for these earlier empirical findings. At the same time, it has become increasingly evident that earlier consensus-oriented perspectives paid insufficient attention to the diverse ways in which individuals, groups, and communities experience disasters. In contrast with classic studies, newer research has emphasized those diverse experiences. Research has also shown how disaster-related experiences are shaped in important ways by the same dimensions of stratification and inequality that influence people's lives during non-disaster times. Disaster scholarship now recognizes that factors such as wealth and poverty, race and ethnicity, gender and age influence vulnerability to hazards, disaster victimization, and disaster recovery outcomes (Blaikie et al. 1994; Peacock, Morrow, and Gladwin 1997; Bolin and Stanford 1998; Fothergill 1998). As a consequence of these developments, disasters are no longer seen as producing common or typical challenges for at-risk populations. While morale and cohesiveness may undoubtedly be high within some groups within a disaster-stricken community, other groups may be excluded. Postdisaster experiences that are therapeutic for some may be corrosive for others. Some groups may be able to return to their pre-disaster status with relatively difficulty, while others may never fully recover. And to a greater degree than has been recognized before, disasters may become arenas not only for consensus-based social action but also for contentious intergroup interactions. Measures taken to deal with disasters may be welcomed by some groups but denounced by others. Relief programs may benefit some within the population while disadvantaging others Research also shows that groups are differentially vulnerable and also differentially resilient in the face of disasters, depending upon their position in the stratification system. The sections that follow discuss recent advances in the study of the social factors that affect disaster vulnerability and that contribute to resilience in the face of disasters. Using examples from both Hurricane Katrina and other U.S. disasters, these discussions illustrate how large-scale social trends, structural forces, and group characteristics influence preparedness for, responses to, and recovery from disasters. A key point made in these discussions is that while Hurricane Katrina revealed the devastating consequences of social inequality more vividly than any recent U.S. disaster, Katrina has a great deal in common with other disasters the nation has experienced. One implication of these findings is that diverse patterns of vulnerability and resilience must be taken into consideration both in programs that provide disaster aid and in overall planning frameworks for disaster loss reduction. Copyright