We can now return to the interpretive challenge posed in the Introduction–understanding the sources of ethnic differences–by considering at once the school and work experiences of the four ethnic groups we have studied in detail. Many early efforts to grapple with the sources of ethnic differences appealed to biological explanations. Later efforts stressed how different cultures encouraged different beliefs, attitudes, and values. Much recent work has concentrated on “structural” or “compositional” explanations–on the extent to which a group's location in the American social structure explains its differences from others. These structural explanations focus on a group's social-class composition and may also include typical family size and structure, educational attainments, geographic concentration, and the like.

An emphasis on structural location need not, of course, preclude attention to other factors, such as pre-migration cultural attributes or discrimination against a group. These sources of behavior may all interact, of course (as sociologist Stephen Steinberg and social historian John Bodnar have stressed). Nevertheless, current discussions that stress structural location typically minimize the independent roles played by other sources of ethnic behavior (except racial discrimination against blacks). One reason they do so is no doubt the intellectual context of their work–the need to counteract both the earlier emphasis on cultural attributes and the persistent strength of ethnic stereotypes in popular thinking.