Code-switching (CS) is frequently used in English as a Foreign Language classrooms (EFL) serving different discourse and educational functions. This paper reports on a case study investigating the forms and functions of code-switching used by the students and the teachers in EFL classrooms in a Turkish university, where the language of instruction was English. Data were gathered from two advanced classes, two pre intermediate classes and one intermediate class through video-recordings. The data obtained from these recordings were transcribed and analysed using the transcription software EXMARaLDA. The results suggest that the most frequent form of code-switching was observed to be using discourse markers. Both the teachers and students used code-switching in the classes for educational and communicative reasons, in particular, to achieve better communication, to deliver content, and to deal with classroom management problems. Implications of the findings for educators and language learning contexts are also discussed. (c) 2021 Elsevier Inc. All rights reserved.