A critical review of some quantitative empirical studies of racial residential segregation, principally Negroes in Cities: Residential Segregation and Neighborhood Change, by Taeuber and Taeuber, which uses an "index of dissimilarity" as the principle independent variable. Index values specify the percentage of population of either race that would have to move from one block to another to bring its residential distribution into line with that of the other race. With this measure, racial residential segregation was not greatly different among the 109 cities studied. The variance in the changes of many cities is largely explained by a number of independent variables in a regression analysis. Other indices that have been used to compile trend series are discussed. The author comments on the ethnic segregation studies of Kantrowitz and compares the differences in philosophy and methodology between his work and a recent study by Pascal.