The University of Iowa

Research Brief: Predicting Dyslexia With Assessments of Foundational Reading Skills

Student and researcher conducting reading assessment

A study by Crystle Alonzo and colleagues looked at assessments of phonological awareness and word recognition given to kindergarteners with and without developmental language disorder to see how well they predicted dyslexia in second grade.


Posted on: October 6, 2020

Editor’s Note: This blog post is part of an ongoing series entitled “Research Briefs.” In these posts, we identify new research studies that are relevant to literacy instruction, summarize their findings, and explain important implications for practitioners.

Article Summarized in This Post

Alonzo, C. N., McIlraith, A. L., Catts, H. W., & Hogan, T. P. (2020). Predicting dyslexia in children with developmental language disorder. Journal of Speech, Language & Hearing Research63, 151–162.

Accurate and timely identification of students with reading disabilities is important for ensuring all children have the supports necessary to become successful readers (Jenkins et al., 2007). This can be a complicated process because reading disabilities exist along a continuum of less- to more-severe problems in one or more domains of reading such as decoding, fluency, and comprehension (Fletcher et al., 2011). This means there is no single pattern of performance that identifies students with reading disabilities. In addition, students may have other disabilities that are related to reading, such as a developmental language disorder (DLD; Adlof, 2017). Individuals with DLD have serious difficulty understanding or using spoken language that is not attributable to other causes such as brain injury, hearing loss, or cognitive impairment (Leonard, 2014).

One of the more common reading disabilities among all children, and particularly those with developmental language disorder, is dyslexia (Hulme & Snowling, 2017). Dyslexia results from a phonological processing deficit that affects decoding, fluent reading, and spelling abilities. Therefore, screening for dyslexia routinely involves assessing students’ phonological awareness, or the ability to identify and manipulate the sounds of words (Melby-Lervåg et al., 2012). Because phonological awareness does not involve referring to printed letters or words, it may not be the best means of predicting students’ ability to read printed words a couple years later. Therefore, Crystle Alonzo and the coauthors of this study examined how well phonological awareness and letter identification skills in kindergarten predicted students’ word reading skills and identification as having dyslexia in second grade.


The subsample of data analyzed for this study was taken from a larger, longitudinal study of language disorders. There were 473 children who had data from both the kindergarten predictor assessments and the outcome tests administered in second grade. After excluding 26 children with nonverbal IQ scores below 70 (meaning an intellectual disability could not be ruled out), there were 187 remaining in the sample who had been identified with developmental language disorder and 260 who were considered to have typical language ability.

Phonological awareness was assessed with a measure that required students to delete a syllable or phoneme from a stated word and then produce the remaining sounds in the word. The letter identification test required students to name individual letters of the English alphabet presented in different typefaces. Word reading skill in second grade was assessed with a measure that required students to identify regular English words presented in isolation, beginning with easier or more common words and gradually progressing to words that are used less frequently. The authors conducted two types of analyses with the scores obtained from these measures. The first looked at how well phonological awareness and letter identification scores predicted word reading scores for students identified as having dyslexia or not. To account for students falling at different points along the continuum of reading ability and disability, the other analysis examined how well phonological awareness and letter identification scores predicted word reading scores across the range of word reading performance.

Findings: Predictors by Student Characteristic

Overall, the results supported letter identification in kindergarten as the stronger predictor of second-grade outcomes. However, there were some differences in outcomes based on student characteristics and analysis type. In the first analysis that explored the prediction of which students will earn a score designating they have dyslexia or not, the authors found that only letter identification significantly and uniquely predicted dyslexia among children with developmental language disorder. However, both phonological awareness and letter identification significantly predicted dyslexia among second graders who had typical language ability.

In the second analysis, performance on the letter identification measure in kindergarten was the stronger predictor of average and lower-ability word reading among second-grade students with DLD as well as their peers with typical language ability. Phonological awareness weakly predicted the later word reading of children with developmental language disorder across all ability levels.


Although their sample was large, the authors acknowledged that the archival data they used meant that they relied on older test forms and norms that are not current. In addition, there were not multiple measures of phonological awareness or word reading used in the study, even though there are different aspects of these skills that an individual may or may not have developed. Therefore, the study should be replicated with more modern tests that examine a variety of abilities and current norms for interpretation. Finally, the authors point out that their study cannot address why letter identification was the better predictor or why phonological awareness was not well related to later word reading ability, especially among children with developmental language disorder. More research is needed to understand the mechanisms involved to improve how students are identified and taught.

Implications for Planning Interventions

Phonological awareness is one of the most common assessments to screen for reading disabilities and dyslexia in particular (Melby-Lervåg et al., 2012), so the authors raised the possibility that the practice may result in many students identified with a disability when they do not, in fact, have one. Adding a letter identification assessment would improve the screening process, but the authors noted two potential drawbacks. First, letter identification can be influenced by home literacy practices such that children from homes where, for example, they play more alphabet games, may have scores that are higher and less indicative of actual ability. Second, merely teaching letter names does not make for better readers. Thus, there is a risk that testing letter knowledge may make teachers think they need to spend more time drilling students on the letters at the expense of other types of instruction.


It is important to keep in mind the various reading skills that may distinguish students experiencing different types of difficulties. Assessing students in only one way will not be sufficient for ensuring accurate and early identification of all students who might need reading intervention. As we at the Iowa Reading Research Center have consistently emphasized, it is important not to use only one piece of data when making big decisions about students.


Adlof, S. M. (2017). Understanding word reading difficulties in children with SLI. Perspectives of the ASHA Special Interest Groups, 2(1), 71–77.   

Fletcher, J. M., Stuebing, K. K., Barth, A. E., Denton, C. A., Cirino, P. T., Francis, D. J., & Vaughn, S. (2011). Cognitive correlates of inadequate response to reading intervention. School Psychology Review, 40, 3-22.

Hulme, C., & Snowling, M. J. (2017). Reading disorders and dyslexia. Current Opinion in Pediatrics, 28, 731–735.   

Jenkins, J. R., Hudson, R. F., & Johnson, E. S. (2007). Screening for service delivery in an RTI framework: Candidate measures. School Psychology Review, 36, 560–582.

Leonard, L. B. (2014). Children with specific language impairment (2nd ed.). MIT Press.

Melby-Lervåg, M., Lyster, S. A. H., & Hulme, C. (2012). Phonological skills and their role in learning to read: A meta-analytic review. Psychological Bulletin, 138, 322–352.