The current prevalence of DSM-III psychiatric disorders was assessed using the Diagnostic Interview Schedule (DIS) as part of a Los Angeles household population survey. The Los Angeles prevalence estimates were compared with sex- and age-adjusted estimates from four other US field sites, all of which were part of the Epidemiologic Catchment Area (ECA) program. Overall, few significant differences in household population rates were found between Los Angeles and the other ECA sites. Within the Los Angeles household sample, the current prevalence of disorder among Mexican Americans was compared with that among non-Hispanic whites. Non-Hispanic whites had higher rates of drug abuse/dependence than Mexican Americans; the rates among non-Hispanic whites in Los Angeles were also higher than those found at other ECA sites. Mexican Americans displayed higher rates of severe cognitive impairment, a finding that likely reflects ethnic and educational bias in the measurement of cognitive impairment. Another ethnic difference was found only for one specific age and sex group: Mexican-American women 40 years of age or older had strikingly high rates of phobia.