Critical neuropsychological capabilities such as working memory, cognitive flexibility, and processing speed are foundational to many daily activities. For children, such skills are essential for school success. Thus, children who demonstrate weaknesses in these abilities may experience impaired academic performance; this is especially true for students identified with learning differences who often exhibit less developed cognitive abilities. The purpose of this project was to examine the efficacy of a cognitive training program implemented during the school day to improve abilities predictive of academic achievement. Ninety-five children completed two training activities that were counterbalanced across participants. Analyses of baseline working memory, cognitive flexibility, and processing speed performance relative to those following training showed a strong treatment effect. Moreover, there is notable evidence of greater intervention efficacy with extended engagement with the training program. Implications for neuropsychological research and practice are discussed.