Why what we teach depends on when: Grade and reading intervention modality moderate effect size.

Despite impressive advances in the science of reading intervention, how to best help at-risk readers remains a point of contention. Because reading represents the synthesis of background factors and language and reading skills-all of which develop with age and experience-this meta-analysis investigated whether development (as approximated by grade) and intervention modality are key moderators of intervention effect size for disadvantaged readers. Eighty-five experimental or quasi-experimental studies with 116 treatment-control groups (N = 7,522) were selected from preschool to Grade 7. Analyses accounted for intervention length, instructor-to-student ratio, measure design, experimental design, attrition, intervention language, and publication bias. Between-group comparisons suggested that effect sizes were larger for older students, comprehension interventions, quasi-experimental studies, and samples at greater risk. In hierarchical regression analyses, intervention modality alone did not explain additional variance in effect size; however, when interacting with grade, intervention modality did explain additional variance. Phonics interventions were more effective until Grade 1, after which comprehension and mixed interventions, in particular, tended to be associated with greater effect sizes. These results highlight the importance of a developmental understanding of reading remediation.