Killingly and colleagues conducted a systematic review and meta-analysis of school-based interventions for students with reading difficulties in Grades 4–12 published between 2011 and 2023. The study examined the overall effectiveness of these interventions and further tested whether study characteristics, sample characteristics, and intervention characteristics moderated their effects. A total of 104 publications and 586 effect sizes were included, representing 97,114 participants. Methodologically, the authors used a Correlated and Hierarchical Effects model combined with robust variance estimation to address dependency among multiple outcomes and effect sizes within the same study, while also estimating effects across overall reading performance and specific reading domains.
The results showed that, overall, reading interventions had a small but significant positive effect for students with reading difficulties in Grades 4–12, with an overall effect size of g = 0.212 (95% CI [0.163, 0.261], p < .001). This suggests that although the gains were not large, these interventions did produce reliable improvements in students’ reading performance. Across specific reading domains, the strongest effects were found for vocabulary (g = 0.422), followed by decoding/word recognition (g = 0.199) and reading comprehension (g = 0.187). Fluency showed only a very small but significant effect (g = 0.080), spelling was not significant (g = 0.015), and phonological processing, although showing a larger effect size on the surface (g = 0.531), did not reach significance and was therefore considered unstable. Overall heterogeneity was very high (I² = 89.71%), indicating that differences in study design and sample characteristics had a substantial influence on intervention effectiveness. GRADE assessment further suggested that the overall quality of evidence ranged from moderate to high, with the strongest evidence for fluency, moderate evidence for vocabulary, and moderate-to-low evidence for phonological processing.
Moderator analyses showed that intervention effects varied according to both study and sample conditions. Overall, more recently published studies showed stronger effects (β = 0.015), and journal articles produced significantly larger effects (g = 0.268) than research reports (g = 0.062). In terms of sample characteristics, low socioeconomic status was not significantly related to overall effects, but a higher proportion of students with learning disabilities was associated with slightly stronger effects (β = 0.006). For students from a language background other than English, overall differences were not significant, but in the vocabulary domain, a greater proportion of such students was associated with stronger effects (β = 0.016), suggesting that vocabulary instruction may be particularly important for this group. Regarding intervention design, intervention focus, duration, and measurement type were all significant moderators. Comprehension-focused interventions showed relatively strong overall effects (g = 0.313), multicomponent interventions showed stable effects (g = 0.178), and word study interventions had smaller effects (g = 0.096), whereas vocabulary-focused interventions, though fewer in number, showed the largest effect (g = 0.716). Shorter interventions were actually associated with stronger effects, with effect sizes of g = 0.405 for 0–5 hours and g = 0.409 for 6–15 hours. In addition, researcher-developed measures yielded significantly larger effects (g = 0.542) than standardized measures (g = 0.127). Although there was no significant overall difference between interventions delivered by teachers and those delivered by researchers, in vocabulary interventions teacher-led delivery produced stronger effects (g = 0.733) than researcher-led delivery (g = 0.249), suggesting that classroom teachers may hold particular advantages in providing vocabulary support.
Overall, this study shows that reading interventions for older students with reading difficulties are indeed effective, although the magnitude of their effects depends on the reading domain being targeted and on the design of the intervention. Vocabulary and reading comprehension appear to be the most promising focuses, while multicomponent interventions also demonstrate stable benefits. By contrast, fluency, spelling, and phonological processing still require stronger evidence from high-quality research. The findings also suggest that these interventions can be implemented across different grade levels and instructional settings, and may be especially beneficial for students with learning disabilities and those from a language background other than English. The authors therefore argue that schools should not assume that older students have missed the critical window for intervention, but instead should select more targeted comprehension, vocabulary, word study, or multicomponent approaches according to the specific nature of students’ reading difficulties, while continuing to build a stronger evidence base to support reading remediation in the upper grades.
Source (Open Access): Killingly, C., Matheson, S., Bentley, L., & Swanson, E. (2025). Interventions for students with reading difficulties in Grades 4-12: A systematic review and meta-analysis. Educational Research Review, 100758.