English has been referred to as a lingua franca for the Association of Southeast Asian Nations (ASEAN). As the region moves towards establishing the ASEAN Economic Community (AEC), the diversity of pronunciation of the ASEAN member states is seen as a forefront issue for English language teaching (ELT). From a sociocultural perspective, this study explored teachers' cognitions about pronunciation instruction and their classroom practice. The findings were based on qualitative data collected from three pre-service non-native English teachers. All the findings were based on these multicultural and multilingual context. Data were obtained from interviews and practicum-teaching observations and were coded and analysed thematically to understand the teachers' emic perspectives of pronunciation instruction. Four themes emerged from the data and were discussed in relation to the 2015 AEC, based on which I challenge the current status of English as a foreign language in the Cambodian ELT mindset. Briefly, these themes include the teachers' self-acknowledgement of their own pronunciation, the perceived goal of pronunciation instruction, their approaches to teaching pronunciation and their attitudes towards ASEAN English as a lingua franca (ELF). The article concludes with implications for English language teacher education in Cambodia and beyond and calls for more research to expand the ASEAN ELF literature.