Learning to be literate builds upon existing knowledge of the language from speech. Becoming literate then enables children to learn more about language. However, literacy is unlikely to be achieved without explicit and prolonged instruction. This review provides an evidence base for decision-making during literacy education. The authors identify key skills that must be in place to enable children to reach their optimum potential and highlight where weakness can suggest a need for extra support. They begin by discussing models of literacy development as these models provide a framework within which to present the evidence base for the rest of the review. They then consider the underlying skills in greater depth, beginning first with the proximal factors that underpin word-level and text-level reading and writing. Then they consider distal child-based and wider environmental factors that indirectly impact on literacy development. [For the related guidance report, see ED612217.]