ln this case study, we have focused on the disempowerrnent of a Korean English teacher (KET) in English-only classrooms. Six English as a foreign language (EFL) classrooms in a Korean high school were observed and analyzed by using interpretive discourse analysis. Out of the six classes, three representative classrl。이ns were both video- and audio - ta많d. The results show that the English-only classes co띠d weaken the KETs’ power via three mechanisms: (a) ca!ling the KETs’ last name for chor외 greetings at the beginning of the class, (b) students’ group solidarity and 야er pressure between classmates, and (c) the students' excessively collaborative approach to 야er assistance. It is argued that the exclusive Engush-oruy instruction disempowers 비e KETs’ status and dismantles their vocational identity. ln order to remedy the current situation, within a scaffolding suppαted by the eclectic use of first language where necessary for effective class management, KETs are empowered and overcome constraints imposed by the limited L2 oral competence of some non-native English teachers.