'Language is like a boat that carries content': Understanding students' and lecturers' perceptions on English medium instruction (EMI) teaching and support in Vietnam and Thailand

English medium instruction (EMI) booms worldwide, yet there remains a lack of support for university lecturers, particularly in Southeast Asia. This study explores the characteristics considered to be important in EMI lecturers and available support and training in Vietnam and Thailand. Questionnaires with students (n=406) and teachers (n=100), 96 interviews and 14 focus groups with students and teachers at 17 universities reveal a complex picture of the characteristics deemed important for EMI lecturers. Our study highlights a need for support to integrate content and language learning and offers implications for staff recruitment and sustainable professional development for EMI teaching. • EMI growth outpaces teacher training in Southeast Asia • Students value subject knowledge more than native-like English • Institutional EMI training focuses too much on language skills • EMI staff feel unprepared to support students' English needs • Local expertise is undervalued in EMI recruitment practices