ABSTRACT This study compared domestic and international students regarding their self-evaluated English proficiency, language performance in English-medium instruction (EMI) classrooms, and their language beliefs. They were enrolled in an English-taught program (ETP) in a Japanese university. EMI courses and programs have strategically increased to attract overseas students and improve domestic students’ English proficiency. Despite extensive EMI research, few studies have focused on EMI experiences of both domestic and international students. Thus, the study analyzed online survey responses from 84 domestic and 24 international students, mostly from Asia. Noticeably, domestic students rated their English proficiency lower than their L2 English international group. Also, the former group found it significantly difficult in performing language tasks, compared to the latter group. Critically, L2 English international students preferred first language (L1) English-speaking instructors and expect non-L1 English lecturers to use native English, whereas Japanese students showed appreciation of lecturers using their L1 in EMI context.