The level of fluency in the genre specific language of schooling, also known as Academic English (AE), determines students’ success in school. Government agencies that legislate school policies therefore give teachers the directive to conduct education in ways that promote communicative abilities in academic English across all curricula. While the acquisition of an AE register entails hard work for native English-speaking students it presents an enormous challenge for English language learners (ELLs) who are faced with the triple burden of leaning basic interpersonal communicative skills (BICS) in addition to content knowledge and academic English. Classroom practices, teachers’ training, and students’ cognitive abilities are predictive factors in the successful acquisition of academic English by ELLs. This literature review, which draws on cognitive theory in addition to systemic functional linguistics theory, contributes to the topic of how to most effectively teach AE to ELLs in English speaking classrooms. The results from seven peer reviewed research sources indicate that teaching practices differ depending on the nature of the subject, but that systemic learning theory, scaffolding, and contextual awareness are reoccurring elements. Furthermore, the results imply that there are challenges including that ELLs constitute a very heterogeneous student body with varying cognitive abilities that require a variety of teaching approaches. In addition educators’ attitudes, competences and training in teaching AE across all curricula pose a challenge to the quality of instruction. Further research on the topic could involve making actual classroom observations in addition to conducting teacher interviews in schools that have content and language integrated learning in Sweden to explore what instructional methods are used to teach AE in CLIL- education.