At the top of the immigration research agenda stands the question of how the newcomers change after they have arrived. The conventional wisdom, both academic and popular, says that immigrants should change by entering the American mainstream. The concept of assimilation stands as a shorthand for this point of view.

In its canonical form, the theory of assimilation began with the assumption that immigrants would arrive as “ethnics,” an identity reinforced by their tendency to recreate their own social worlds. Cultural change would come first, as Americanization made the second generation quite different from their forebears in tastes, everyday habits, and preferences. But Americanization could proceed even as the ethnic social structure of interpersonal relations largely stood still: as long as immigrants and their descendants remained embedded in ethnic neighborhoods, networks, and niches, integration into the fabric of American society would have to wait. Once ethnic boundaries were crossed, however, increasing exposure probabilities to outsiders would inevitably pull ethnic communities apart: with the move from ethnic ghetto to suburb, interethnic friendships, networks, and eventually marriages would all follow in due course. Thus, the advent of structural assimilation, to borrow the influential term coined by Milton Gordon, signaled entry into the “mainstream,” and the beginning of the end for any distinctiveness associated with the immigrant generation (Gordon 1964).

All this is now entirely familiar to the students of American ethnicity.