Social science research on natural disasters documents how a natural hazard such as a hurricane becomes a disaster through social processes and social structures that place human populations in general, and certain segments in particular, at risk. After a description of Hurricane Katrina and its impact, we describe how patterns of land development, and the economic and political history of New Orleans, set the stage for this disaster. An overview of past research findings on the relationship between citizen vulnerability and poverty, minority status, age and disability, gender and tenancy is followed by evidence of the extent to which each risk factor was present in the pre-Katrina New Orleans population. The authors then cite evidence of how social vulnerability influenced outcomes at various stages of the Hurricane Katrina catastrophe, including mitigation, preparation, evacuation, storm impacts, and recovery. The concluding section discusses how the goal of disaster resilient communities cannot be reached until basic issues of inequality and social justice are addressed.