The main objective of this research is to analyze the school interaction of a deaf student in a context that is practically unexplored in Brazil: the classes of English as a foreign language in the first segment of elementary school in an inclusive public school. Specifically, we seek to investigate: (i) how the deaf student co-constructs knowledge in a multilingual context with three languages in contact (English, Portuguese and Libras), plus the home signs brought by the deaf student and non-verbal language that composes the interactional scenario; (ii) how the deaf student s interaction with the other participants – the English teacher, the hearing peers, and the educational interpreter – impacts the co-construction of knowledge. The theoretical-methodological approach is Applied Linguistics in the scope of Classroom Microetnography, with a qualitative-interpretative-naturebased case study, carried out in a first-year class of elementary school in an inclusive municipal school in Rio de Janeiro called Bilingual education school (Libras-Portuguese). The data was generated in 2018. In the first months, the researcher set the scene in the school, with observations of the school routine and the target English classes, recorded in fieldnotes. During this period, semistructured interviews were also carried out with the pedagogical coordinator of the school, the English teacher of the target group, the deaf student and the person who is legally in charge of him, in order to map the school context, the characteristics of the participants and their perspectives about the research object. After these months, audio-visual records of English classes were taken in the target group, from which two were selected for analysis: one class without the presence of the educational interpreter and the other with her presence, which made possible a comparison among the structures of participation in each situation in order to identify possible impacts of these different settings in the co-construction of knowledge by the deaf student. Data were transcribed through conventions of conversation analysis and studies on Libras. Data analysis indicates that in the interaction with the English teacher, his hearing peers, and the interpreter, the deaf student builds affectivities and demonstrates knowledge about classroom interactional patterns. With the educational interpreter, in particular, despite the great resistance waged by the student, there is co-construction of knowledge in Libras and about Libras. There is no evidence, however, of co-construction of knowledge in English or about English, which may be the result of the methodological approach used, which is based on orality, and therefore does not contemplate the specificities of the deaf student. There are, thus, many challenges faced by all the participants of the research and, mainly, by the deaf student in which concerns the construction of knowledge. The results of the study may contribute to reflections on the process of inclusion of the deaf student and the need for methodological appropriateness regarding the teaching of oral-auditory foreign languages for the deaf of the first segment of elementary school in an inclusive context, which lacks research and makes this study a pioneer in the field.