Abstract
The use of English has rapidly been growing in the Expanding Circle of world Englishes. This situation is especially true in Vietnam. In order to know what affects the use of English, including its role in code-switching in classrooms in Vietnam, a case study was conducted to address the main question, “What is the impact of the tertiary education context on code-switching in classrooms in Vietnam?” The subject was one teacher of two English classes (one in a public university and the other in a private one). The data for this study include document analysis, classroom observations, the teacher’s stimulated recalls, and the students’ written feedback. The study found that more code-switching (CS) happened in the public school than in the private school due to (1) the in-class time budget, (2) the students’ English levels, (3) cultural factors, (4) the teacher-evaluation system, and (5) teacher cognition. The study also found that inter-sentential CS was dominant compared to intra-sentential CS.