This research was conducted in Vietnam, responding to a practical situation as most teachers of English failed to attain the B2 standard of the Common European Framework of Reference for Languages. It presents findings regarding the characteristics of these teachers' process of English proficiency development. From the analysis, four themes emerged: the spontaneity of teachers' learning, three motivational factors driving English proficiency development, the dominance of traditional over internet-mediated learning activities and the popularity of individual rather than collaborative learning activities. The paper conceptualizes teachers' development in a model with four continua which can cater for the differences between individual teachers and also allow shifts on these axes as the English proficiency development activities and motivations change over time. The paper ends by emphasizing the need to listen to teachers' voice to understand their English development before long-term and meaningful support programs can be drafted.