Social vulnerability is a term describing how resilient a community is when confronted by external stresses on human health. These stresses can range from natural or human-caused disasters to disease outbreaks. By reducing social vulnerability, we can decrease both human suffering and economic losses.

The Social Vulnerability Index (SVI) employs U.S. Census Bureau variables to help users identify communities that may need support in preparing for hazards or recovering from disasters. The tool is particularly useful for emergency response planners and public health officials, as it can identify and map the communities that are most likely to need support before, during, and after a hazardous event.

The SVI uses U.S. Census Bureau data to determine the social vulnerability of every census tract (census tracts are subdivisions of counties for which the Census Bureau collects statistical data). The SVI ranks each tract on 14 social factors, including poverty, lack of vehicle access, and crowded housing, and groups them into four related themes. Each tract receives a separate ranking for each of the four themes, as well as an overall ranking.