This study objective to investigate the discourse functions of code-switching used by the teachers in ESL classrooms in a Pakistani university. Another aim of this study was to find out the forms of code-switching used by the teachers and functions of these code-switching usages at diploma level. In the light of these aims, four diploma classes were observed and audio recorded. The data obtained from these recordings were transcribed using the content analysis method and the following results have been obtained: 1) teachers use code-switching in the classes for educational and social reasons; 2) the most frequent form of code-switching was observed to be used discourse markers. Keywords: Function of Code-switching, Classroom discourse
