The importance of the concept of professional identity lies in its relationship to professional knowledge and action, but these links are complex. A traditional notion of identity is of something essential about ourselves, a fixed and stable core of "self". More recently, however, identity has been seen as an ongoing and performative process in which individuals draw on diverse resources to construct selves. This process is seen as emerging in and through narratives of practice. This paper, based on research into teachers' professional identities in relation to behaviour management, presents a narrative analysis showing how "Dan" draws on available resources to construct himself as a teacher and how this process is shaped by the institutions in which he is situated.