ABSTRACT: Suburbanization is changing the face of urban America. A common claim is that suburban sprawl has contributed to increasing levels of economic segregation, but few studies have directly tested this hypothesis. Using U.S. Census data for 1990 and 2000, this paper examines the trends in and the relationship between suburban development patterns and economic segregation in U.S. metropolitan areas. We find that economic segregation, as measured by the Neighborhood Sorting Index (NSI), declined during the 1990s, reversing the earlier trend. However, results from cross-sectional and fixed-effects regression models at the metropolitan level suggest that suburbanization, as measured by five different indicators, was a countervailing influence during the decade. Metropolitan areas that were suburbanizing more rapidly had smaller declines in economic segregation than comparable metropolitan areas.