The aim of this study was to investigate the role of intergenerational health-related mobility in explaining social-class inequalities in alcoholism among young men. Data on social class of origin and on risk factors in childhood and adolescence, e.g. risk use of alcohol, were collected for 49,323 men, born 1949-51, at enlistment for compulsory military training in 1969/70. Information on achieved socioeconomic class was obtained from Sweden's 1975 census. Data on alcoholism diagnoses were collected from the national in-patient care register 1976-83. Risk indicators for alcoholism established in adolescence were found to be more common among downwardly mobile individuals, and also among stable manual workers, than among those who ended up as non-manual employees. Downwardly mobile individuals, and also stable manual workers, were also found to have an increased risk of alcoholism diagnosis. The increased relative risk could, to a considerable extent, be attributed to factors from childhood/adolescence. In this longitudinal study, it is shown that intergenerational social mobility associated with health-related factors, albeit not with illness itself, made a major contribution to explaining differences in alcoholism between social classes. Factors established in adolescence were important with regard to differences in alcoholism between social classes among young adults. But such adverse conditions did not seem to be well reflected by social class of origin.