Medical care practitioners, especially physicians, work with other practitioners in three roles: as colleagues, supervisors, and competitors. These roles have become more important as medical care delivery moves from the small private physician’s offices to managed and team care settings. As supervisors, practitioners must comply with same workplace laws and regulations as supervisors in non–medical care businesses, while also dealing with the issues that are unique to medical care delivery. These include the duty to consult with other practitioners when it is necessary for a patient’s welfare, the duty to ensure that subordinates and other team members deliver good medical care, and that state and federal law and regulations are followed.