The study is concerned about investigating how interactions between deaf and hearing students and hearing teacher are carried out in an undergraduate course where Libras, Portuguese and other forms of language are used, including code-switching and code-blending. The research is justified by the recent and growing contingent of deaf youngsters and adults who enter higher education in Brazil, a phenomenon of the socio-economic context of transition, in the context of socio-cultural and historical transformations, initiated especially with the recognition and regulation of the use of Libras by Federal Law 10,436 in 2002 and by the Federal Decree 5,626 in 2005. In theoretical terms, the study seeks to articulate concepts of Interaction Sociolinguistics, Conversation Analysis in an institutional context, and Languages in Contact in interaction, on the micro and macro levels, as they pertain to Deaf Studies. The methodology of the research is qualitative and interpretative, with data recording employing an ethnographic research method. Seven interactions were recorded and analyzed in seven different classes in which ones the researcher has acted as teacher. It is important to highlight, in the conventions of transcription, the discussion about the need to adapt the existing models of conventions in oral and sign language to the specificities of speech in interaction with deaf and hearing people in a multilingual context, with languages in contact. From the discussion, a new model of conventions of transcription was proposed, for oral language and sign language, with a focus on interaction. In the data analysis, transidiomatic practices emerged as communicative repertoires of the participants. Two chapters were established, from seven interactions. The first of these chapters, chapter 4, focusing on interactions 1 and 3, was mainly devoted to students frames, with a focus on the entry in the Letras-Libras Course. The results indicate that students construct self-identities out of the focus on other students and of the groups themselves. They also point out the student s professional expectations regarding course options. The results of chapter 5, from interactions 2, 4, 5, 6 and 7, indicated, above all, the co-constructed relationships in the classroom between teacher and deaf and hearing students into transidiomatic practices that that have produced the bi-multilingual character of the classroom. They showed differences among students in propensity to adhering to the institutional frames, with conflicting relationships and the search for linguistic affirmation among the students, as well as co-construction of knowledge between teacher and students. Although the teacher, as an institutional representative, had chosen Libras as the language of instruction, in the data analyzed, the languages in contact in the classroom indicated multilingual practices on the part of the students, who used Libras, Portuguese and other mixed forms of language. The research suggests the necessity to generate reflections on how students perceive the entry into a Letras-Libras Course and how the teacher and students understand what is happening in the here and now of this undergraduate classroom in a socio-educational context under construction, which proved to be multilingual in the transition in recognition of deaf subjects as a linguistic minority.