This book enquires into the politics and practices of international literacy assessment programmes, exploring how the internationally comparable numbers, now so heavily relied on in national policy are produced, and how they are shaping our understanding of the meanings and purposes of literacy. The collection brings together leading international academics in this field and representatives from key policy and literacy assessment institutions to identify a future research agenda for the field of International Assessment Studies. It illuminates the amount of (often invisible) work that goes on behind the scenes in producing the tests and the policies.