Decisions about what constitutes appropriate medical care are increasingly necessary in an aging society. Neither patient autonomy, physician beliefs, nor health services research alone can adequately define reasonable care for the individual patient. A new framework is proposed for determining reasonable medical care that involves 4 steps: (1) patients prioritize their goals of care (prolongation of life, maintenance of function, and maximization of comfort); (2) physicians assign a pathway of care based on the patient's prioritization of goals (longevous, ameliorative, or palliative); (3) expert panels define a range of feasible interventions for each pathway; and (4) medical problems are treated with interventions consistent with the pathway chosen. The pathway system has the potential for defining reasonable care by balancing the patient's view, the physician's view, and evidence from the clinical literature.