This paper, Using Effect Size as a Comparative Metric of Academic Achievement, introduces a practical and equitable way for educators and policymakers to compare school performance beyond traditional proficiency scores. By using effect size—a standardized measure that accounts for demographic differences such as economic disadvantage—the paper demonstrates how schools can be evaluated on a fairer playing field. Readers will gain a clear, step-by-step understanding of how to calculate and interpret effect sizes, see visual examples of their application, and learn how this approach complements proficiency metrics to paint a more complete picture of student achievement. Download the paper and the accompanying data to explore how this method can help you make more informed, equitable comparisons across schools and districts.