There is growing evidence that childhood socioeconomic position (SEP) influences adult health. The authors' aim was to describe the association between childhood SEP measures (parents' education, occupation, and income) and mortality, for both genders, and to assess to what extent this association was mediated by adult SEP. Registry data for all Norwegians born in 1955-1965 were used. Death records were linked to the cohort, and 6,589 persons died during 1990-2001. Cox's regression was used to calculate relative rates and the relative index of inequality. Low childhood SEP was associated with increased mortality for most causes of death, except for breast cancer, where no association was found. For suicide in women, low childhood SEP was protective. Adult SEP accounted for the associations for total mortality and most causes of death. However, adult SEP accounted for only one half of the association of father's educational level with ischemic heart disease mortality among men. The increased suicide risk among women with high childhood SEP persisted, regardless of adult SEP. In summary, childhood SEP had a direct association with early adult cardiovascular mortality in men and with suicide in women. For other causes of death, childhood SEP was only indirectly associated, mostly through persons' own educational level.