The aim of this study was to examine the relationship between housing conditions, educational level, occupational factors, and serologically diagnosed acute and chronic Helicobacter pylori infection. IgG, IgM, and IgA antibodies against Helicobacter pylori were measured by ELISA techniques in sera obtained from a random sample of 3589 Danes participating in a population study. Poor social status (odds ratio 2.2 [1.7-3.0]), short duration of schooling (odds ratio 2.0 [1.3-2.5]), lack of vocational training/education (odds ratio 1.4 [1.2-1.7]), unskilled work (odds ratio 1.7 [1.2-2.5]), and high work-related energy expenditure (odds ratio 1.4 [1.1-1.9]) increased the likelihood of chronic Helicobacter pylori infection. Chronic Helicobacter pylori infection was frequently found in people with a history of living abroad. Increased levels solely of IgM antibodies to H. pylori, interpreted as a sign of acute infection, were found more often in people who were divorced (odds ratio 2.3 [1.2-4.4]) or unmarried (odds ratio 2.0 [1.1-3.8]) and in people who worked long hours (odds ratio 2.0 [1.1-4.0]). In conclusion, educational and occupational factors relate to the likelihood of chronic Helicobacter pylori infection in adults. The rate of acute Helicobacter pylori infection is probably increased in single adults.