Emerging from the growing body of work on English medium instruction (EMI) in higher education are challenges to policy implementation, particularly when it is implemented top-down without a careful needs analysis or when it fails to address problems associated with ‘English-only’ implementation and so-called ‘native speaker’ norms. Our study responds to this need by exploring the role of English in EMI classrooms. We draw on data collected from 17 universities in Thailand and Vietnam using questionnaires with 1,377 students, 83 teachers of English for academic purposes (EAP), and 148 content teachers, as well as interviews with 35 students, 31 EAP teachers, and 28 content teachers. We also draw on data from 14 focus groups with teachers and students at seven universities in Vietnam. Findings reveal differences in attitudes amongst stakeholders and highlight that the L1 in EMI classrooms in Thailand and Vietnam, albeit used sparingly, is a useful pedagogical tool. Overall, however, participants preferred native-accented teachers with experience abroad, and English-only instruction. This study calls for more research into raising awareness of Global Englishes and translanguaging practices to challenge such attitudes, university language policies, and teacher recruitment practices that seem to reflect native-speakerism and discourage bilingual instruction or L1 use in EMI classes.

高等教育中越来越多的英语媒介教学 (EMI) 工作对政策实施提出了挑战，特别是当它在没有仔细需求分析的情况下自上而下实施时，或者当它未能解决与“仅英语”相关的问题时实施和所谓的“母语人士”规范。我们的研究通过探索英语在 EMI 课堂中的作用来满足这一需求。我们利用从泰国和越南的 17 所大学收集的数据，对 1,377 名学生、83 名学术英语教师 (EAP) 和 148 名内容教师进行问卷调查，并对 35 名学生、31 名 EAP 教师和 28 名内容教师进行访谈. 我们还利用了来自越南七所大学的 14 个焦点小组的数据。调查结果揭示了利益相关者之间的态度差异，并强调了泰国和越南的 EMI 课堂中的 L1 尽管使用较少，但却是一种有用的教学工具。然而，总体而言，参与者更喜欢具有海外经验的母语教师和纯英语教学。本研究呼吁开展更多研究，以提高对全球英语和跨语言实践的认识，以挑战这种态度、大学语言政策和教师招聘做法，这些做法似乎反映了母语，不鼓励在 EMI 课程中使用双语教学或 L1。