With the increasing dominance of English in many domains of language use including education, and in line with the continued expansion of English Medium Instruction (EMI) in higher education, English is now seeking a standing as a language of education in schools of non-Anglophone countries beyond postcolonial settings. Although different aspects of school-level EMI have been investigated, following mainstream trends in applied linguistics and language education, these investigations tend to focus on linguistic and instructional challenges. Critical sociolinguistic concerns surrounding school EMI such as issues of language ideologies and learner/teacher identities have been marginally addressed. Therefore, in light of a critical view of EMI, in this study I examined the opinions and attitudes of EMI teachers in a secondary school in Hong Kong about the sociopolitics of teaching school subjects in English to students who speak it as an additional language. The main set of data comprised interviews with 22 EMI teachers in a local secondary school which offers an EMI stream for international and ethnic minority students along with Cantonese medium classes. The analysis of interviews through inductive coding procedures led to the emergence of six themes that portray different aspects of the participants’ critical awareness of EMI or lack thereof: Clear emphasis on the necessity of English; Rough understanding of the influence of English on identities; Vague interest in multilingualism and multiculturalism; Little awareness of international policies of spreading English; Little idea of how such policies can be encountered; and Cautious interest in receiving support for critical teaching. I discuss some aspects of these views within the wider context of language education ideologies and policies in Hong Kong and some insights that can be gained in this postcolonial setting in relation to the sociopolitics of the further dominance of English (in education) worldwide.