A fundamental goal of many smart growth efforts is to promote greater socioeconomic equity through more compact development. In this article, we point out that the connection between the built environment and socioeconomic outcomes may be more complex than it is generally portrayed to be, particularly in light of recent trends in urban and regional development.Through an empirical analysis involving two measures of income segregation, dissimilarity and isolation, in a national data set of metropolitan areas from 1980 to 2000, we illustrate that the relationship between density and income segregation follows a quadratic function, first rising, then falling, as densities increase. Moreover, changes in density-whether increases or decreases-always increased segregation. These findings suggest that, if greater socioeconomic equity is a goal, smart growth programs need to pay as much attention to market forces and the underlying political landscape as they do to the built environment.