Beyond phonemic awareness: The alphabetic principle predicts reading acquisition in a nationwide longitudinal study

Phoneme awareness (PA) is undoubtably the most important and well-studied predictor of reading development. Yet, 20 years ago, Castles and Coltheart made the provocative claim that there was no convincing evidence for the causal role of PA in learning-to-read because previous studies typically failed to control for pre-reading skills. In the present study, we leveraged a unique opportunity to analyze data from a large-scale longitudinal investigation of reading development conducted nation-wide among all first graders in France (i.e., N = 810,328 children). We estimated not only the direct effect of PA on reading fluency measured one year later, but also its interaction effects with letter-knowledge (LK), knowledge of the alphabetic principle (KAP), and oral comprehension (OC). Our results show that the direct effects of PA on later reading fluency are moderated by OC, LK and KAP. Specifically, PA contributes to later reading outcomes only among children with strong KAP, and good LK and OC. We highlight the central role of KAP as a key predictor that has often been acknowledged in theory but rarely measured in empirical research. These findings indicate that phoneme awareness supports reading development only in the context of sufficient alphabetic knowledge, challenging strong causal accounts of PA in early reading acquisition.