The objective of the present study was to compare data on the prevalence of mental illness in Germany and the United States. For this purpose, data from the Upper Bavarian Study (UBS) and the Epidemiologic Catchment Area (ECA) are presented and compared. In both studies, personal interviews were administered to a sample of community residents. The UBS sample consisted of 1,847 persons aged ≥18 years, and the ECA study consisted of 24,371 household members aged ≥18 years in five sites; 1,876 persons from the ECA sample lived in rural sites, and they were used for comparison with the (rural) UBS sample. The diagnostic classification (according to DSM-III) obtained by clinical interviewers in the UBS and by lay interviewers in the ECA was used. The total 6-month prevalence for any axis I Diagnostic Interview Schedule mental disorder (corrected for sample stratifications and adjusted for age) was 18.5% in the (rural) UBS, 18.0% in the total ECA sample (five sites), and 13.4% in the rural sites of the ECA. High morbidity rates for substance use disorders (UBS, 5.8%; ECA rural sites, 3.4%) and affective disorders (UBS, 6.8%; ECA rural sites, 4.1%) were observed in both studies. The 6-month prevalence rates for alcohol use disorders (3.1% considered marked or severe) were 5.1% in the UBS and 2.9% in the ECA rural sites. Concerning anxiety disorders (UBS, 1.6%; ECA rural sites, 6.7%) there was a substantial difference between the studies, which mainly resulted from a higher prevalence of phobia in the ECA program. There were higher rates of dysthymia (3.8% considered marked or severe) in the UBS (5.4%) than in the ECA rural sites (2.6%), whereas the rate of major depression was somewhat lower in UBS (1.4%) as compared with the ECA rural sites (2.4%). Alcohol use disorder was the most frequent category of mental disorder for men in both studies; for women, affective disorder and phobia (in the ECA) were the most frequent categories. Despite differences in methodology concerning sampling, instruments, and case identification, the similarities between the results of the two studies were considerable.