Can American health insurance survive? In The Transformation of American Health Insurance, Troyen A. Brennan traces the historical evolution of public and private health insurance in the United States from the first Blue Cross plans in the late 1930s to reforms under the Biden administration. In analyzing this evolution, he finds long-term trends that form the basis for his central argument: that employer-sponsored insurance is becoming unsustainably expensive, and Medicare for All will emerge as the sole source of health insurance over the next two decades. After thirty years of leadership in health care and academia, Brennan argues that Medicare for All could act as a single-payer program or become a government-regulated program of competing health plans, like today's Medicare Advantage. The choice between these two options will depend on how private insurers adapt and behave in today's changing health policy environment. This critical evolution in the system of financing health care is important to employers, health insurance executives, government officials, and health care providers who are grappling with difficult strategic choices. It is equally important to all Americans as they face an inscrutable health insurance system and wonder what the future might hold for them regarding affordable coverage.