Children who are at-risk for reading difficulties (RD) lag behind their peers in academic achievement and this achievement gap may grow over time (Morgan, Farkas, & Hibel, 2008; Stanovich, 1986), resulting in a lifelong condition that negatively impacts academic achievement, employment opportunities, and social interaction. Consequently, remediating reading difficulties is a paramount goal of education, requiring research that disentangles the causes and symptoms of reading difficulties and develops effective treatment.

RD can involve difficulties with reading at the word level or language processing level. Some children have specific comprehension difficulties (e.g., Cain & Oakhill, 2006; Hulme & Snowling, 2011), while children with word level difficulties (decoding and/or word recognition) may have comprehension difficulties largely as a result of word-level deficits (e.g., Garcia & Cain, 2013; Gough & Tunmer, 1986). In the general population, estimates of reading difficulty in children at the word level (often referred to or thought of as synonymous with dyslexia) range from 6 to 17% (Fletcher, 2009) and these children typically have a phonological processing deficit (S. E. Shaywitz & Shaywitz, 2005; Torgesen et al., 1999). Children with word-level difficulties tend to be identified during the early elementary years (Nation & Snowling, 1997; Shankweiler et al., 1999), though some do not experience difficulties until late elementary or middle school years (Catts, Compton, Tomblin, & Bridges, 2012; Compton, Fuchs, Fuchs, Elleman, & Gilbert, 2008; Leach, Scarborough, & Rescorla, 2003; Lipka, Lesaux, & Siegel, 2006). To minimize the reading deficits that may otherwise impede their progress, children with RD need evidence-based reading intervention.