This paper aims at discussing teacher identity based on Cultural Studies. We take the idea that the postmodern subject is fragmented, destabilized, in the middle of an identity crisis (HALL, 2003). Subjects, therefore, are constituted by language in the spaces of social interaction in their relation to others, school being one of these spaces. In order to carry out this research, we propose a case study involving a teacher that teaches both Portuguese as L1 and English as L2 in a public elementary school in Rio Grande, Rio Grande do Sul. Considering the linguistic forms found in her speech, we discuss her representations as a teacher, her students and the implications of such representations to the teaching-learning process by the cross examination of the following data collection instruments: a written interview, a recorded and transcribed oral interview and field notes. The theoretical framework used includes Cultural Studies, from the viewpoint of Stuart Hall (2003), in order to discuss the identities, and Systemic-Functional Grammar, by Halliday and Matthiessen (2004), as a linguistic approach which sees the data in relation to the context and its linguistic forms. For the analysis, we use the three metafunctions of Systemic-Functional Grammar.