<p>The validity of the screening tools used as a part of assigning students to tiers within the Three Tier framework is essential for its quality and success. Although the Three Tier model has been widely implemented, there remains a lack of comprehensive synthesis regarding the accuracy of screening methods used as part of tier assignment procedures. This systematic review and meta-analysis examined empirical studies on the validity of screening and progress monitoring tools in the domains of literacy, language, and mathematics. A comprehensive search of seven databases and search engines yielded 127 eligible studies. The majority of tools identified were used in the literacy domain, with the Dynamic Indicators of Basic Early Literacy Skills (DIBELS) being the most frequently employed. Of the included studies, 18 studies provided data on convergent validity, including concurrent or predictive correlations, and sensitivity and specificity metrics. Using a correlated-hierarchical effects robust variance estimation (CHE-RVE) model, results indicated a moderate overall pooled effect size for correlations (<i>r</i> = .51, 95% CI [.35, .64], <i>p</i> = .001). However, this estimate should be interpreted cautiously, as heterogeneity was very high. Sensitivity and specificity estimates also varied widely across different tools. Findings highlight the limited number of studies assessing the validity of screening tools. Given the central role of screening in identifying students with learning difficulties, further research is needed to improve the precision and reliability of these instruments.</p>