We examined the double deficit hypothesis (Wolf & Bowers, 1999) and literacy development in a longitudinal dataset of 1,006 Finnish children who were nonreaders at school entry. A single phonological awareness (PA) deficit was a predictor of pseudoword spelling accuracy and reading fluency, and a single rapid automatized naming (RAN) deficit was a predictor of reading fluency. The group with both PA and RAN deficits experienced the most extensive reading and spelling difficulties. However, all groups included both poor and average Grade 2 readers and spellers. Poor letter knowledge and vocabulary, task avoidance, attention difficulties, hyperactivity, and lack of teaching at home were additional risk factors for reading and spelling problems, but their impact varied depending on the presence of PA and RAN deficits.