Many features of Hodgkin's disease (HD) among adolescents and young adults suggest that it has an infectious etiology. However, the proposal that HD is a contagious disease which can be transmitted by patients or their close contacts has not been substantiated. An alternative infectious disease model is suggested by analogy with paralytic poliomyelitis (PP). For both diseases, the peak age of incidence is delayed as living conditions improve. For both, increased risk is associated with higher social class and small family size. Like PP, HD may be a rare manifestation of a common infection with the probability of disease development increasing as age at infection is delayed. This analogy is supported by the report that the risk of HD is higher for persons who had a low frequency of childhood infectious diseases. If this model is valid, HD patients represent no hazard to their contacts. However, the incidence of HD among young adults may increase in the coming decade because of the current high standard of living and small family size.