In response to the global expansion of the English language, several conceptual and analytical paradigms--World Englishes (WE), English as a lingua franca (ELF), and English as an international language (EIL)--have been developed to study the pluricentricity of English and its pedagogical implications. English language teacher education programmes need to challenge language ideologies that promote native-speakerism and monolingualism, acknowledge the plurality of the English language and its speakers, and promote respect for such plurality. However, these implications are still notably absent in many English language teacher education programmes. Programmes that do include courses on English language variations are either too theoretical or have constructed this variation from a deficit lens. In this article, undergirded by the EIL paradigm, the author proposes to detail an institutional approach to designing an EIL-informed professional development course which aims to theoretically and practically inspire in-service English language teachers in the Southeast Asian region to legitimately acknowledge the plurality of English, and to translate such awareness into classroom practices. The article specifically delves into a curriculum crafted to achieve this aim. Additionally, it presents feedback from Singapore in-service English teachers in order to gain insights into the course's impact on their convictions about English, and on their classroom practices. It ends with a discussion on this feedback as well as of the study's limitations.