This chapter focuses on an innovation that has been achieved through a one-year in-service English language teacher education (LTE) program in Seoul, Korea, nicknamed “Snowball”. It briefly reviews theoretical tools crafted internationally and relevant empirical findings and interpretations garnered domestically in the field of English LTE. It then elaborates on the details of the impetus for the innovation, which crucially included a master teacher’s first-hand experiences of English (teacher) education in Korea and her realization that ordinary English LTE programs were not quite effective for actual classroom improvement. It then relates what proposal she made and was accepted by an education research official in the Seoul Education and Training Institute, which gave birth to the Snowball program featuring participants’ learning by doing, instant feedback, and a long-term engagement. This chapter then depicts the details and results of the program, whose success factors include customized special interest groups, long-term action research, abundant sources of inspiration, and a culture of sharing. It finally presents some lessons learned on LTE: The importance of learner-centeredness, autonomous teacher research into genuine problems, screening participants, support for participants’ genuine learning communities, and their chances for re-establishing pedagogical core values.