This volume presents recent developments in identity theory and research. Identities are the basic building blocks of society and hold a central place in every social science discipline. Identity theory provides a systematic conceptualization of identities and their relationship to behavior. The research in this volume demonstrates the usefulness of this theory for understanding identities in action in a variety of areas and settings. The volume is organized into three general areas: ethnicity and race; family, religion, and work; and networks, homophily, and the physical environment. This comprehensive and authoritative volume is of interest to a wide readership in the social and behavioral sciences, including students and researchers of sociology, social psychology, psychology, and other social science disciplines.