This guidance report aims to help secondary schools improve literacy in all subject areas. It provides seven recommendations related to reading, writing, talk, vocabulary development and supporting struggling students. Throughout the report, recommendations emphasise the importance of disciplinary literacy. Disciplinary literacy is an approach to improving literacy across the curriculum. It recognises that literacy skills are both general and subject specific, emphasising the value of supporting teachers in every subject to teach students how to read, write and communicate effectively in their subjects. This guidance challenges the notion that literacy in secondary school is solely the preserve of English teachers, or literacy coordinators. The emphasis on disciplinary literacy makes clear that every teacher communicates their subject through academic language, and that reading, writing, speaking and listening are at the heart of knowing and doing Science, Art, History, and every other subject in secondary school. [For the three other companion reports in this series, see Improving Literacy in Key Stage 1 (ED612212); Improving Literacy in Key Stage 2 (ED612216); and Preparing for Literacy: Improving Communication, Language and Literacy in the Early Years (ED612218). For three related evidence reviews, see Writing Approaches in Years 3 to 13 (ED612219); Literacy Development (ED612220); and Reading Programmes for Secondary Students (ED612242).]