Professor Hershberg (History, Univ. of Pennsylvania) and his colleagues on the Philadelphia Social History Project believe they are fighting an uphill battle against those intellectual purists whose first response to interdisciplinary research is, ""This isn't history"" (or whatever-the-field). This is history, and it's solid history, based on a massive set of censuses, city directories, and other records, and on the combined talents of assorted historians and social scientists. But in answer to the question Hershberg considers paramount--namely, ""Has this collaboration resulted in a significant expansion of the frontiers of knowledge?""--the answer has to be no. Much of the same ground has already been covered by historians such as Sam Bass Warner (The Private City) and Herbert Guttman (The Black Family in Slavery and Freedom); and some of the controversial ideas examined-e.g., that blacks are best considered the latest immigrants to the city, due in time to rise like the immigrants before them--have already been effectively dowsed. Nonetheless, the articles do serve to flesh out the larger-scale studies and do succeed in demonstrating how, in Philadelphia, ""the forces that shaped modern America--urbanization, industrialization, and immigration--operated for blacks within a framework of institutional racism and structural inequality."" In ""Industrial Location and Ethnic Residential Patterns,"" sociologist Stephanie Greenberg shows how location of work and industry was the primary factor behind community formation, with ethnicity figuring in only secondarily: a conclusion which undermines our image of the solid, 19th-century immigrant ghetto. Few blacks, however, could get jobs in industry, even when they did live in the immediate neighborhood. Hershberg and fellow-historian John Modell, and sociologist Frank Furstenberg, also find blacks differing from the immigrant populations through their nigher rate of female-headed households; but they agree with Herbert Guttman that the causes are not rooted in the slave past or cultural preference but are ""decidedly urban and structural""--high mortality rates for blacks, imbalanced sex ratios, and poor working and living conditions, among them. In considering the various ""family strategies"" that groups adopted to deal with poverty, economist Claudia Goldin points to yet another difference: while immigrant families sent their cildren out to work in order to keep the wife at home, black families did just the opposite, in part because of labor force discrimination against black children, in part because of the greater willingness of black women to go out to work. Besides such conclusions relating to ethnic and racial group experience, the authors draw others concerning the process of industrialization itself: that it occurred at an extremely uneven rate in the various crafts and industries; that increase in scale did not always bring increase in profits per unit input, but was pushed by the captains of industry nonetheless. Philadephia thus does not so much ""extend the frontiers of knowledge"" as fortify areas already partially settled. Solid and worthwhile, even if no great breakthroughs are in evidence.