This 2011 dissertation, conducted during the 2010-11 academic year at over 30 primary schools in Italy, examined the effect of chess instruction on mathematics achievement for third grade students. In each participating school, one third grade class was randomly assigned to receive in-class chess instruction, receiving approximately 30 hours of instruction throughout the year from certified staff. 950 students were enrolled in the treatment classrooms, with a control group of 806 students. A math assessment designed by the author was given to all third grade students in the treatment and control classrooms at the beginning and end of the academic year. The study found that participation in chess instruction increased math scores, with students in the south of the country and foreign-born students showing greater gains than their northern and native counterparts. The effect size of the math growth caused by the chess program was 0.340, or approximately one third of a standard deviation, and is statistically significant. This study was eligible for inclusion in the systematic literature review and categorized as a Tier I study. However, the results may not be generalizable to other schools, as participating schools were recruited through the author’s network and were not randomly chosen for participation.