A decade of field work and statistical data from the Cornell Studies in Intergroup Relations culminates in this comprehensive documentation of social structures and strictures in the United States today. Some twenty cities were covered methodically, with intensive studies conducted in four: Savannah, Georgia; Elmira, New York; Bakersfield, Calif.; and Steubenville, Ohio. The results from the field workers and the carefully formulated house-to-house questionnaire presented in tabular form support the more general explanations and conclusions about ethnocentrism, prejudice and the complex social organization that engenders them. Among the minority groups studied -- Negroes, Jews, Mexican-Americans -- the Negroes were found to be the targets of the most rigid segregation and discrimination and form therefore the major topic in the report. With the most advanced sociological methods (and jargon), concepts such as social distance and stereotyping are treated in strict connection with the data. Although no treatise on social reform is intended, the conclusions are that cooperative activity toward a common objective between different ethnic groups tends to result in increased social solidarity. A particularly fine and respectable presentation, this study might well serve as a model of its kind --more, readable and commonsensical than the usual IBM tabulations in contemporary sociological archives.