This is the first comparative analysis of the role and performance of private health insurance (PHI) in OECD countries. The book reviews PHI markets and identifies policy issues arising from their interdependence with public health coverage schemes. It assesses the impact of PHI on health policy objectives, paying special attention to the challenges and benefits associated with different insurance mixes. In addition to identifying strengths, it also explores areas where private health insurance might pose challenges to health system performance. Examples of useful practices for developing an efficient and equitable health insurance market are also presented. This thorough analysis shows how governments can help ensure that PHI markets contribute to the performance of health systems.