Two methods have been developed for using the Minimum Data Set (AADS) to estimate cognitive ability, the Cognitive Performance Scale (CPS) and the MDS Cognition Scale (MSD-COGS). The relative utility of the two scales was compared by correlating them with the Mini-Mental State Exam the Global Deterioration Scale in a sample of 290 nursing home residents with a mean age of 87 years. Both the CPS and the MDS-COGS related quite strongly to the Mini-Mental State Exam and to the Global Deterioration Scale, with the MDS-COGS correlating at slightly higher levels than the CPS. The CPS and the MDS-COGS both provide a simple, straightforward method of assessing cognitive function that is easy to understand and clinically meaningful. Because both are derived from the MDS, administration costs, as compared with that of the Mini-Mental State Exam or the Global Deterioration Scale, are also substantially lower. Inasmuch as the data are already available and the procedure is so simple (particularly with the MDS-COGS), it might be of benefit to include a computation of cognitive function as part of the MDS profile.