The purpose of this study is to investigate the relationship between early life socioeconomic status, household structure and adult all cause and cause-specific mortality in Finland during the latter half of the twentieth century. We base the analyses on a 10% sample of households drawn from the 1950 Finnish Census of Population with the follow-up of household members in subsequent censuses and death records beginning from the end of 1970 through the end of 1998. The Finnish data constitute a unique register based data set that does not rely on individual recall of early life social conditions, parental educational attainment, family type, and other life course trajectories. We find significant associations between early life social and family conditions on all cause mortality as well as mortality from cardiovascular and alcohol related diseases, accidents and violence; with protective effects of higher childhood SES varying between 10% and 30%. These associations are mediated through adult educational attainment and other socio-demographic characteristics. The results imply that long-term adverse health consequences of disadvantaged early life social circumstances may be mitigated by investments in educational and employment opportunities in early adulthood.