Teacher Bilingual Ideology as Catalyst in EAP: Influencing Chinese Graduate Students’ Language Beliefs

English for Academic Purposes (EAP) courses primarily aim to cultivate academic communication, yet English-only norms and exam-oriented histories often discourage bilingual participation. This qualitative study traced Chinese graduate students’ language-belief development over one semester in a graduate EAP course and examined how the instructor mediated that process. Data included two rounds of open-ended surveys in two intact classes (N = 40), two interview rounds and end-of-semester reflections from ten purposively selected focus students (n = 10), and video-recorded classroom observations of 12 lessons. Findings show that the students increasingly legitimized bilingual participation and reframed English learning from test preparation toward academic communication. Beliefs nevertheless remained layered. Many still upheld an English-only ideal, treated English as the default language, and positioned the first language (L1) mainly as support when second language (L2) expression became difficult. Endorsement also exceeded uptake, with L1 use treated as a compensatory fallback rather than a co-equal academic resource. Instructor policy, conceptual framing, and interactional modeling reduced anxiety around bilingual moves and sometimes supported greater willingness to attempt more English, which identifies mechanisms for bilingual-aware EAP pedagogy in monolingual-leaning EFL contexts.