Using the 1980 census's independent measures of race, Spanish origin, nativity, and ancestry, this paper describes racial differentiation and segregation in 21 metropolitan areas, comparing it with ethnic group segregation, and to other demographic and housing characteristics. Special attention is given to the interplay of race and poverty. Examination of statistics dealing with Blacks, Asian Americans, American Indians, Hispanics, and Whites reveals that the races are sharply separated in the American metropolis, at a level of segregation outstripping most other attributes (dealt with here under four headings: socioeconomic status, life cycle, ethnicity, and housing) except for the physical characteristics of the housing stock. Further, racial segregation serves to reinforce the separation of the poverty population, highlighting the degree to which poor members of minority groups are removed geographically as well as socially from the mainstream. Following the narrative portion of this report, which combines technical information with broad summarization of findings, three statistical tables are presented: (1) "Dissimilarity for Race, Spanish Origin, and Nativity"; (2) "Dissimilarity for Single and Multiple Ancestry"; and (3) "Dissimilarity for Poverty Status by Race." Two charts are also included: "Mean Index of Dissimilarity for Race, Spanish Origin, and Ancestry" and "Mean Entropy Statistic for Selected Characteristics." (KH)