This article describes how students in an urban Catholic school draw on racial and religious categories to construct classroom-specific identities during coursework. When students engage with each other in classroom discussions, they use broadly circulating, institutional, and event-level categories to position one another, and in doing so articulate who may speak and participate in class talk. This paper draws from interactional ethnographic data, showing how Vietnamese American and African American students used different religious and racial categories to delimit the interactional floor during class time and in the process exclude speakers.