We outline how research into predictors of literacy underpins the development of increasingly accurate and informative assessments. We report three studies that emphasize the crucial role of speech and auditory skills on literacy development throughout primary and secondary school. Our first study addresses the effects of early childhood middle ear infections, the potential consequences for speech processing difficulties and the impact on early literacy development. Our second study outlines how speech and auditory skills are crucially related to early literacy in normally developing readers, whereas other skills such as motor, memory and IQ are only indirectly related. Our third study outlines the on-going impact of phonological awareness on reading and wider academic achievement in secondary-school pupils. Finally, we outline how teachers can use the current research to inform them about which assessments to conduct, and how to interpret the results. (Contains 4 figures, 3 tables and 4 notes.)