The concrete-representational-abstract (CRA) approach is an instructional framework for teaching math wherein students move from using concrete materials to solve problems to using visual representations of the materials, and finally abstract concepts. This study provides a literature synthesis and meta-analysis of the effectiveness of the CRA approach as a math intervention. Thirty studies using single-case design methodologies were included. Descriptive analyses of the study variables are discussed. Results indicated a statistically significant overall Tau-BC effect size of 0.9965, 95% CI [0.9947, 0.9983], p < 0.0001. A meta-regression of eight potential moderator variables suggested that using a non-integrated CRA approach increased the overall effect size by 0.011, 95% CI [0.007, 0.015], p = 0.045. Implications of using the CRA approach for researchers and educators are discussed.