Along with survival and other types of clinical outcome, the functioning and well-being that characterize end-stage renal disease patients are important indicators of the effectiveness of the medical care that they receive. In addition, maximizing functioning in chronically ill patients can be viewed as secondary prevention. Patient-reported functioning and well-being indicate how patients are doing in their daily lives and how they feel about their lives. Measurements used to assess patient functioning and well-being by health services researchers are applicable to health outcome assessment in the clinical setting. Disease- and treatment-specific outcome measurements are more sensitive to disease severity and treatment intervention effects, while generic outcome measurements provide generalizability across diseases or conditions. Specific measurements can provide data about clinically meaningful changes, and generic measurements help to indicate the significance of these outcomes in patients' daily lives. Using both types of patient-reported measurements, as well as performance-based assessments, will provide outcome-based data on end-stage renal disease patients' functional limitation and disability, and help to define relevant rehabilitation protocols for end-stage renal disease patients.