Published in 2012, this study evaluated the impact of an in-school chess intervention on Iranian students’ math achievement and cognitive development in grades 5, 8, and 9. The randomly assigned sample was comprised of 86 treatment group students and 94 control group students. Students were tested on an author-created math assessment and a cognitive assessment during the study’s six month duration. The authors conducted a test of statistical significance on mean test scores, and found an effect size of 0.686 standard deviation units on the math assessment and an effect size of 0.819 standard deviations on the cognitive assessment. The results were statistically significant. The study was eligible for inclusion in the systematic literature review and categorized as Tier I since it used random assignment.