Homogamy (husband-wife similarity in a specific trait) requires consideration in connection with psychological theories of types, in the study of the origin and maintenance of social classes, in the statistical analysis of heredity, in psychoanalytic and other studies of social relationship in the home, in the investigation of marital infection in tuberculosis and other diseases, and in evolutionary and eugenical theory. A review of prior research shows a tendency to a slight marital resemblance in physical traits, with husban-wife correlations for stature, eye-color, etc., averaging about .25. Early studies of resemblance in mental traits give, for the most part, similar coefficients, but these are probably attenuated to a marked degree by the unreliability of the rating methods used. A series of recent surveys, making use of more adequate mental test methods, place the marital coefficient in intelligence at approximately .5. Similar values are found in widely different social samplings. This is approxim...