This book describes how social identification and academic learning can deeply depend on each other, both through a theoretical account of the two processes and a detailed empirical analysis of how students' identities emerge and how students learn curriculum over a year in one classroom. The book traces the identity development of two students, showing how they came habitually to occupy characteristic roles across an academic year. The book also traces two major themes from the curriculum, showing how students came to make increasingly sophisticated arguments about them. The book's distinctive contribution is to show in detail how social identification and academic learning became deeply interdependent. The two students developed unexpected identities in substantial part because curricular themes provided categories that teachers and students used to identify them. And students learned about those curricular themes in part because the two students were socially identified in ways that illuminated those themes.