Using multiply imputed data from 5 waves of the National Longitudinal Survey of Youth (N = 8,294), we investigated whether childhood family characteristics and childhood religious affiliation explain ethnic differences in marijuana and cocaine use in the last year. None of the childhood factors explained ethnic differences in drug use, though ethnicity and several childhood factors had age-specific effects. Over the life course from young adulthood to middle age, ethnic differences in drug use changed and the effect of childhood religious affiliation declined. Having a more intellectually rich family in childhood increased the risk of drug use at younger ages but reduced it at older ages. The study demonstrates the significance of childhood family experiences for understanding adult drug use.