This paper explores teachers' resistance against pedagogic reform in South Korea, which was instituted in the form of an in-service teacher certification. Ideas for the reform, Teaching English in English (TEE), were borrowed from "native-English-speaking countries" and implemented without systematic localization, therefore, it was not surprising that teachers resisted it, although hidden from the reform managers to avoid disciplinary action. The paper starts with a description of the educational context in South Korea, which has fashioned teachers' practices of resistance. The conceptualization of resistance follows, drawing on studies from varied disciplines, including Foucault's work on resistance "of conduct" (counter-conducts) and Scott's "invisible" resistance. Findings from a case study of the TEE certification are then discussed. Teachers were engaged in various forms of low-profile resistance, which culminated to impact on the fate of the certification. The paper highlights the potential impact of resistance on the course of a reform, which has often been disregarded as non-constituent or unimportant or even misunderstood as compliance by reform managers and researchers. Thus, it contributes to a more comprehensive understanding of teachers' resistance in the context of educational reforms, which has wider implications, as borrowed educational reforms are becoming all too frequent around the world.