Despite its many sterling qualities, the nation’s health-care system has become a $1 trillion monster with oversized problems that seem to grow larger by the minute: soaring federal outlays for Medicare and Medicaid, nearly one-sixth of the population without medical insurance, and rising expenses everywhere. Now the system is lumbering in a new direction, toward managed care. Appraising this new destination—with all its implications for patients and doctors, hospitals and researchers—our authors suggest a variety of midcourse alterations.