More and more writers on black America allude to the development of two distinctive Negro classes; William Julius Wilson, a young black sociologist at the University of Chicago, accepts and expands on that thesis and tries to explain its basis by tracing black social structure. The plantation system and white working-class racism, though able to frustrate black ambitions from slavery to World War II, are of little consequence today. Rather, the continued presence of a black poor ""under-class"" stems less from racism than from structural, color-blind weaknesses in the economy. These deficiencies have allowed for the creation of two black working classes: one integrated, unionized, and secure in the advanced industries that require well-trained employees; the other poor, unorganized, and disproportionately black, unemployed, or toiling in menial service-sector jobs with few chances for upward mobility. Current trends that the author finds have little to do with racism--particularly the relocation of industries out of the central city and the vocational education required in the work place--keep this second class down. Some readers will vehemently disagree with the author's underplay of racism: did white workers, for example, accept suburbanization largely because the work place shifted, or to escape minority groups? Questionable too is his view of technology as an independent, irresistible force, since its diffusion can be tied to managerial responses to alterations in work force composition and education (e.g., the constantly increasing disadvantage of inner-city blacks). One also challenges the need for the extended historical sections, since from the very outset Wilson describes his two-tier ""modern industrial"" class system as one which evolved only after World War II. Even here Wilson has limited his researches to the most prominent historical and economic studies, some of which are not the most relevant to his purposes (e.g., the Gutman and Genovese works on slavery). Nevertheless Wilson's basic contention is arresting and complemented by a straightforward style; data presentations are limited and all intelligible. Avoiding the rubric of racism as an explanatory device, this compellingly logical presentation leads the reader to conclude that aiding poor blacks will require more than a change in the hearts and minds of white America.