This paper describes one way in which students develop durable, classroom-specific identities. When students enter new groups 8 their identities are often fluid. Over time, however, students and teachers generally come to identify individuals in predictable ways. 9 Durable identities emerge across events, as signs of identity come to presuppose a consistent trajectory of identification for a given 10 individual. This paper traces the social identification of one student across the course of a two-month curriculum unit in a middle 11 school science class, showing how he developed a complex but robust identity across several weeks in a new lab group.