This paper reports on a research study using the Butlerian notion of performativity in the analysis of school librarian identity. The purpose is to explore how librarians at secondary and upper-secondary schools perform their identities as school librarians. Fourteen in-depth interviews were conducted. The analysis was driven by the theoretical concepts of performative identity, recognizability and intelligibility. Performing identity was found to be part of six work-tasks: to express, to position, to make visible, to remind, to inform and to explain. In conclusion, the study contributes to research on school librarian challenges, pursuits and strategies when performing professional identity in relation to teachers. Focusing on the performative acts of school librarians can contribute to understandings of their everyday challenges and deepen the understanding of the profession.