Both income inequality and income segregation in the United States grew substantially from 1970 to 2000. Using data from the 100 largest metropolitan areas, we investigate whether and how income inequality affects patterns of income segregation along three dimensions—the spatial concentration of poverty and affluence; race-specific patterns of income segregation; and the geographic scale of income segregation. We find a robust relationship between income inequality and income segregation, an effect that is larger for black families than for white families. In addition, income inequality affects income segregation primarily through its effect on the large-scale spatial concentration of affluence, rather than by affecting the spatial concentration of poverty or by altering small-scale patterns of income segregation.