This study examines dissent between pre- and in-service Korean non-native English-speaking teachers’ (NNESTs) about the monolingual English as a foreign language (EFL) approach, which, according to Cook's recent framework, is founded on four untested, but weighty, enlaced hypotheses in English teaching (i.e. naturalism, native-speakerism, monolingualism, and absolutism). In-service teachers, unlike pre-service teachers, prefer the bilingual approach, which may stem from their effective teaching experience, rather than from teacher factors like the size of experience abroad and English competence.