This study examines the comparative attitudes of students and professors toward English-medium instruction (EMI) policies at Korean universities. Specifically, it investigates these stakeholders’ experiences with EMI implemented in science and engineering universities, the main facilitators of EMI and the internationalization of Korean higher education. Within a mixed method framework, questionnaire surveys were administered to 523 students and 37 professors from three leading science and engineering universities, and supplementary interviews were conducted with nine professors. The results of the analysis show that both professors and students believe that EMI should be continued. With respect to their motivations to engage in teaching and learning subjects in English as a foreign language (EFL), the majority of both groups were involved in EMI due to their university’s policy, with lower satisfaction in EMI classes than in Korean-medium classes. More students than professors were unconvinced of the effects of EMI on their English ability. Notably, despite the inadequacy of their English ability, many students were not enthusiastic about enhancing their levels of English language proficiency. These contradictory views are discussed to propose ways to explicitly promote English language instruction as well as EMI-related professional development for subject professors at EFL higher education institutions.