In this age of multicultural democracy, the idea of assimilation - that the social distance separating immigrants and their children from the mainstream of American society closes over time - seems outdated and, in some forms, even offensive. But, as Richard Alba and Victor Nee show in their systematic treatment of assimilation, it continues to shape the immigrant experience, even though the geography of immigration has shifted from Europe to Asia, Africa and Latin America. Institutional changes, from civil rights legislation to immigration law, have provided a more favourable environment for non-white immigrants and their children than in the past. Assimilation is still driven, in claim, by the decisions of immigrants and the second generation to improve their social and material circumstances in America. But they also show that immigrants, historically and in the contemporary world, have profoundly changed American society and culture in the process of becoming Americans. Surveying a variety of domains - language, socio-economic attachments, residential patterns and inter-marriage - Alba and Nee demonstrate the continuing importance of assimilation in American life. They predict that it will blur the boundaries among the major, racially defined populations, as non-whites and Hispanics are increasingly incorporated into the mainstream.