This document discusses the different roles that physicians can play in a healthcare system. It outlines several key functions that a healthcare system performs, including stewardship, financing, creating resources, delivering services, and responsiveness. For each function, it then describes the main roles of different types of physicians, such as family physicians, clinical specialists, epidemiologists, and others. The roles range from directly delivering clinical services to individuals, to more broad roles in areas like health advocacy, disease management, health policy, resource investment and training, and community assessment and interventions.