The primary objectives of this research were to pilot the use of a new pain and mobility outcome measure, the Pain and Mobility Index (PMI), and to assess its convergent validity with the Short Physical Performance Battery (SPPB). Twenty-eight subjects were divided into nonhospitalized and hospitalized groups. The number of subjects needed for future research using the PMI to assess for rehospitalization risk is at least 124. Discharge SPPB and PMI scores showed a good correlation, and there was a significant difference in bed mobility scores and SPPB scores between the nonhospitalized and hospitalized groups.