The Spanish DIS was applied to a community probability sample in an island-wide survey of the prevalence of psychiatric disorders in Puerto Rico. The prevalence of “severe cognitive impairment” as measured by the DIS Mini-mental State Examination (DIS/ MMSE) is significantly higher than that reported in similar studies in US communities. The total sample (N=1532) was used to study the impact of demographic variables and other psychiatric diagnoses on DIS/MMSE scores. Educational level was by far the strongest predictor of total scores as well as of scores on individual items. Issues are discussed and recommendations are made related to the use of this test in Hispanic populations of low educational level.