Book excerpt: The monumental Harvard Encyclopedia of American Ethnic Groups is the most authoritative single source available on the history, culture, and distinctive characteristics of ethnic groups in the United States. The Dimensions of Ethnicity series is designed to make this landmark scholarship available to everyone in a series of handy paperbound student editions. Selections in this series will include outstanding articles that illuminate the social dynamics of a pluralistic nation or masterfully summarize the experience of key groups. Written by the best-qualified scholars in each field, Dimensions of Ethnicity titles will reflect the complex interplay between assimilation and pluralism that is a central theme of the American experience. The tightening and loosening of ethnic identity under changing definitions of "Americanism" is emphasized in this volume.