The aim of this study is to identify the forms of participation and the ways both teachers and students negotiate meaning as well as reveal the patterns of the multilingual classroom in the Mexican context. This thesis brings to the floor many contextual issues and attempts to link them to what happens in the higher education environments where English becomes a compulsory subject for all disciplines. This descriptive case study focuses on EFL teachers and students in a higher education context in beginning and intermediate levels. This study used a qualitative method research design to gather and analyze data. Audio-recorded classroom observations, field notes and teacher semi-structured interviews were used to capture an emic perspective on what takes place in these EFL classrooms regarding the multilingual resources that these teachers and students use. By examining transcripts of audio-recorded interactions using an applied Conversation Analysis approach of teachers and students, I identify and describe the multilingual resources that are being used to communicate. Semi-structured teacher interviews were used to delve into their views and reasons for certain classroom practices such as code-switching (CS) which was the dominant practice used for diverse communicative purposes as well as other relevant issues such as the English only policy" as it challenged some internalized ideas within the institutional level. The data reveals that both teachers and students draw on CS to reiterate concepts and words, express equivalence, establish group solidarity and discuss procedural protocols to name a few. I will argue that CS is a resource available to participants and that both teachers, policy makers, school authorities and material developers as a more holistic approach in language teaching and learning that takes into account all of the languages in the learner's repertoire.