Ceiling effects limit the utility of many established brief cognitive screening tests for detecting and measuring mild delirious states and prodromal disorders. The High Sensitivity Cognitive Screen (HSCS) (Faust & Fogel, 1989), a bedside test taking approximately 25 minutes to administer, may overcome this limitation. The test consists of a selection of moderately difficult items testing six major domains of neuropsychological performance: memory, language, attention/concentration, visual/motor, spatial, and self-regulation and planning. Reliability is adequate, and two separate concurrent validity studies show accuracy rates of 93% and 87% in classifying the overall result of comprehensive neuropsychological testing. HSCS performance is highly correlated with EEG results in medical psychiatric inpatients, and with functional status in HIV-infected community-dwelling subjects. The brevity and convenience of the HSCS and related instruments make them particularly useful in studies of elderly and chronically ill subjects.