This study aims at investigating the construction of the identities of an English teacher, through the manifestations of her beliefs on talks about textbooks and instructional materials. The research is based upon socioconstructionist identity theories which conceive identity construction as a fluid, multiple and fragmented phenomenon, which is generated in discourse; situated in the context and in the course of the interactions; and built in terms of similarity and difference (DUSZAK, 2002; MOITA LOPES, 2002, 2003; BAUMAN, 2005; BUCHOLTZ; HALL, 2005; HALL, 2005). The theoretical framework is also built on the sociosemiotic approach of language proposed by the Systemic-Functional Linguistics (HALLIDAY, 1989, 1994) and follows a qualitative methodology of research (DENZIN; LINCOLN, 2000). The work was carried out upon a case study with an English teacher during meetings held to discuss the new materials proposed for the new childrens course at a language school in Rio de Janeiro, where I was the academic coordinator in charge of the segment then. The data were analyzed under the light of the Systemic-Functional Linguistics, mainly with the analytical tools of the Appraisal Theory (MARTIN, 2000; MARTIN; WHITE, 2005; VIAN JR., 2009), and they indicate that affection, judgment and appreciation permeate the beliefs which contribute to the teachers identity processes. During these talks, this participant (co)constructed and (re)constructed her identities, reflecting how she sees herself professionally and how she engages with the other participants in the meetings, as well as with the other teachers in the institution and with the students.