The National Institutes of Health Toolbox includes two executive function measures: the Dimensional Change Card Sort (DCCS) and the Flanker Inhibitory Control and Attention Test. Developmental extension (Dext) versions were created with easier levels for younger and more disadvantaged children. Although research on early (E-Prime) and later (iPad) versions of the Dext measures demonstrated their short-term validity, this study investigated their longer-term predictive validity. Participants included 402 children (Mage = 55.02 months) who completed the DCCS-Dext and Flanker-Dext (E-Prime) during early childhood screening and achievement tests in the third grade. Both measures significantly predicted math and reading scores among diverse groups of children.