This volume celebrates identity theory as a leading framework that organizes research on identities across a wide swath of disciplines, such as sociology, psychology, political science, criminology, social work, and education. It positions identity as not merely an abstract concept studied in a vacuum; but rather, as a foundational aspect of our lives that are developed, maintained, and negotiated in real, day-to-day social contexts, and that carry very real implications for health, well-being, future aspirations, and realized successes in a variety of social arenas. Featuring original, empirical work from senior, mid-career, and junior scholars, this volume presents new and cutting-edge developments in identity theory that advance research in the context of higher education, rural communities, political engagement, police-citizen interactions, racial/ethnic minorities, and patients in healthcare settings. Other topics covered include identity development, identity maintenance and negotiation, mental health and wellbeing, and aspirations and success expectations. Many chapters feature continued measurement improvements and/or bridges to other theories. The volume highlights the practical, applied utility of identity research for understanding and contributing to solutions for contemporary social problems. It is essential reading for researchers, academics, and graduate and undergraduate students who are interested in the relationship between identities and social problems and who seek to stay apprised of new and emerging emphases within the identity theory research community.