This paper reports the development of an instrument, the Reintegration to Normal Living (RNL) Index, to assess global function status. Information to determine the components of the index was systematically collected through interviews with professionals, patients, and their significant others, promoting content validity. Psychometric properties of the index were assessed using three samples of patients with varied diagnoses from several settings. The index demonstrates high internal consistency and adequate interrater reliability (patient and significant other). It is responsive to changes in the clinical status of patients, particularly when the subscales of Daily Living and Perceptions of Self are considered. In terms of criterion validity, the index is somewhat related to work status and disease status. It also demonstrates construct validity, both convergent and discriminant, when assessed against a quality of life index and an index of psychologic well-being. The RNL index appears to assess global function and measures both the patient's perceptions of their own capabilities and objective indicators of physical, social, and psychologic performance.