In this 2005 report, the authors evaluated the impact of a one year, after-school chess intervention on 3rd grade Scottish students’ reading achievement (Neale Analysis of Reading Ability), cognitive development (Wechsler Intelligence Scale for Children), and behavior (Bristol Social Adjustment Guide). There were 36 students in the sample—18 in the treatment group and 18 in control group. Control group students were either students from the same school who played computer games or students at different a primary school who did not receive chess instruction or play computer games. Data were analyzed using tests of statistical significance, univariate regression analysis, and multivariate regression analysis. The authors found an effect size of -0.004 standard deviation units in reading, 0.613 standard deviations on the cognitive assessment, and 0.400 standard deviations on the behavioral assessment. However, the results were statistically insignificant suggesting no difference between treatment and control students. The study was eligible for inclusion in the systematic literature review and categorized as a Tier III study. Failure to control for differences in past achievement may have generated biased results.