Systematic inquiry into second language teacher learning has been carried out for 3 decades, but research into learning to teach English pronunciation is just emerging. The purpose of this paper is to address this gap by examining the long-term trajectory of a Japanese teacher of English learning to teach English pronunciation. The case study examined the development of the instructor’s practices and cognition (i.e., beliefs and knowledge) about English pronunciation over a 5-year period. A 13-week pronunciation-pedagogy course, a narrative frame that elicited the instructor’s self-reported pronunciation teaching practices, and 2 classroom observations followed by a semi-structured interview were used to collect data. The findings demonstrated that the 5-year development of the teacher’s practices and cognition was a complicated and non-linear process. Several contextual factors were identified as being responsible for the uneven development of the teacher-participant’s practices, cognition, and uptake of content taught in the pronunciation pedagogy course.