Little is known about the diagnostic validity of the 15-item Geriatric Depression Scale-Short Form (GDS-SF), especially when compared to the original 30-item version (Geriatric Depression Scale-Long Form; GDS-LF). This study compared the GDS-SF and GDS-LF with a sample of depressed, demented, and thought-disordered inpatients. The GDS-SF and GDS-LF were found to be highly correlated (r = .89) and to have similar high sensitivity rates. The specificity rates for both forms were similar, but lower than desirable. Overall, the GDS-SF was found to be an adequate substitute for the GDS-LF.