Book excerpt: The professional learning framework this book presents is designed to support teachers’ understandings of how language functions in their academic disciplines. This framework—a 4 x 4 metalinguistic toolkit—is informed by systemic functional linguistic theory and international educational research on academic and disciplinary literacies. The book shows and explains how teachers have applied specific 4 x 4 toolkits with students in middle school classrooms across a range of subjects for curriculum literacy instruction, assessment and feedback, resulting in substantial growth for their students in high-stakes national tests of literacy, as well as writing assessments in a number of subjects. In its focus on disciplinary literacies in diverse sociocultural settings, Academic Literacies in the Middle Years responds to contemporary international curricula for English language and literacy and the need for a strong evidence base for professional learning design.