Disasters are sudden, unexpected, localized, rare, and acute events that disrupt both the environment and social structure, inflicting substantial harm on individuals, groups, and property. They differ from accidents and emergencies in the greater magnitude of their impacts. The number of disasters has increased, especially since 1990, as posited by risk society and shock doctrine theory. Social constructions of risk, organizational cultures, and concentration of power, population, and strategic resources contribute to disasters, and globalization contributes to their scope. Low- and middle-income countries and socially vulnerable groups and neighborhoods are more likely to be victims of disasters, while the economic costs are greater in higher-income countries. The social mechanisms responsible for the damages of natural, technological, and political disasters may differ. Disasters go through socially structured iterative stages of preparedness, response, recovery, and mitigation, and generate both social solidarity and social conflict. Socially cohesive communities respond faster and recover better. Yet disasters disrupt social bonds and institutions. Uncertainty may lead to rumors spreading about who is responsible, impeding solidarity and preventive measures. Recovery may be uneven, reinforcing inequalities. Recent research has considered the factors that increase individual and community resilience.