The present study examined longitudinal associations between preschoolers' executive function (EF) and adult educational attainment, impulse control, and general health directly and through its cascading effects on childhood and adolescent EF using a large, national, and prospective longitudinal sample of participants. Data were drawn from the National Institute of Child Health and Human Development study of Early Child Care and Youth Development (NICHD SECCYD) and included a diverse sample (52% male at birth; 76% White; 13% Black; 6% Hispanic; and 5% other; 14.23 mean years of maternal education) of 1,364 participants born in 1991 and followed through age 26. Four main findings emerged. First, we observed significant bivariate relations between EF measured at 54 months and adult educational attainment (r = 0.36, p < 0.01), and impulse control (r = 0.11, p = 0.01). Second, early EF measured during preschool and childhood explained variance in adult educational attainment and impulse control above and beyond adolescent EF. Third, childhood EF mediated the association between preschool EF and adult educational attainment and impulse control but did not operate through adolescent EF. Finally, neither preschool EF nor EF measured at other developmental stages predicted health during adulthood. Together, these findings shed light on the direct and cascading influences of EF across development on important domains of adult functioning.