The ability to adjust one’s language according to discourse context is important for all English learners. Prior literature has operationalized two distinct types of language used in contexts: academic language and decontextualized language. Despite their similarities, academic language and decontextualized language have been studied in different strands of research. To bring together the discussion around language use in diverse contexts, this study investigated the commonalities between the two constructs by emphasizing the role of discourse knowledge. In doing this, the current study advanced the theoretical understanding of discourse knowledge by identifying its various aspects such as audience awareness (perspective taking), background knowledge, and genre awareness. Furthermore, pedagogical implications are made regarding how discourse knowledge should be explicitly taught to all learners of English, given its importance.