Th is paper investigates vulnerability and fl ood hazard in two borderland communities. A model for assessing vulnerability is applied to U.S. and Mexican communities of Del Rio and Ciudad Acuña to evaluate the spatial distribution of the characteristics of people, places, neighborhoods, and systems that infl uence the impacts of fl ood events that occur along the Rio Grande/Río Bravo. Spatial data from the U.S. and Mexican 2000 censuses are combined at block group and Área Geográfi ca Estadística Básica (AGEB) scales to evaluate demographic and other descriptors of the areas impacted by fl oods. Th e diff erences between the patterns of vulnerabilities relative to the distribution of fl ood risk in the two cities are highlighted and the implications of these patterns are discussed.