Individual differences in educational attainment (EA) and physical health, as indexed by body mass index (BMI), are correlated within individuals and across generations. The aim of our study was to assess the transmission of these traits from parents to their offspring in childhood and adolescence. We analyzed BMI and EA in 13,916 families from the Netherlands. Data were available for 27,577 parents (mean age 33) and 26,855 of their offspring at 4 and 12 years of age. We employed structural equation modeling to simultaneously estimate the phenotypic transmission of BMI and EA from parents to offspring, the spousal correlations, and the residual child BMI-EA associations after accounting for intergenerational transmission and testing for gender differences therein. We found a significant intergenerational transmission of BMI to BMI in childhood (age 4; standardized regression coefficient β =.10) and adolescence (age 12; β =.20), and of EA to academic achievement in adolescence (β =.19). Cross-trait parent-to-offspring transmission was weak. All transmission effects were independent of parent or offspring gender. We observed within-person EA-BMI correlations that were negative in parents (∼-.09), positive in children (∼.05) and negative in adolescents (∼-.06). Residual EA-BMI were positive in children (∼.05) and insignificant in adolescents. Spousal correlations were.46 for EA,.21 for BMI, and ∼-.09 cross-trait. After accounting for spousal correlations, the intergenerational transmission for BMI and EA is mainly predictive within, but not across, traits. The within-person correlation between BMI and EA can change in direction between childhood and adulthood.