This study investigated the characteristics of effective English teachers as perceived by 169 teachers and 339 students in high school in Korea, with a self-report questionnaire consisting of three categories: English proficiency, pedagogical knowledge, and socio-affective skills. Overall, the teachers perceived significantly different characteristics than the students in all three categories with the teachers ranking English proficiency the highest in contrast to the students who ranked pedagogical knowledge the highest. The student subgroups also held different perceptions of effective teaching. High achieving students reported different characteristics than low achieving students in pedagogical knowledge and socio-affective skills, whereas the male students demonstrated different characteristics from the female students in socio-affective skills. The findings have implications for knowledge-based teacher education for current and prospective English teachers. (Contains 7 tables.)