The intergenerational transmission of low educational attainment is well-documented, but little is known about how behavioral problems in childhood explain this association. Drawing upon a population-based cohort study (n = 3020) linked to administrative records, we investigated the extent to which inattentive, internalizing, externalizing, and prosocial behaviors at child ages 6-8years accounted for associations between parental education and child's risk of failing to graduate from high school. We adjusted for economic, demographic, cognitive, and perinatal factors, as well as parental mental health. Using logistic regressions and the Karlson-Holm-Breen decomposition method, we found that childhood behaviors together explained 19.5% of the association between mother's education and child's high school graduation status at age 22/23, and 13.7% of the association between father's education and this same outcome. Inattentive behaviors were most strongly associated with failure to graduate from high school, while the role of other behaviors was modest or negligible. Inattentive behaviors may represent a mediational pathway between parental education and child education. Early interventions targeting inattentive behaviors could potentially enhance the prospects of intergenerational educational mobility.