Ted Robert Gurr and James Q. Wilson both place an emphasis on the role of moral standards and changing social attitudes. In contrast, the author bases his analysis on Martin Gold's view of the role of socialization. Thus, the decline in homicide within a few years of 1870 resulted from the movement away from pre-industrial forms of education and work and toward three related and highly organized social forms: the factory, the bureaucracy, and the public school. His research has focused mainly on Philadelphia and Massachusetts. His 1986 book on the roots of black violence notes that they were almost totally excluded from office and factory jobs until World War II, so they did not experience the downturn in homicide shown by the Irish and Italian immigrants who took part fully in the new economic order. In addition, since the 1960's, high unemployment and soaring crime rates have been especially marked among young black males in the cities. These analysis show the importance of considering the role not only of urban industrialism but also of trends rather than events and of specific groups and classes rather than large groups, cities, or nations. Figures, tables, and reference notes.