Physician impairment, the inability to carry out patient care responsibilities safely and effectively, is a problem of functioning. However, the presence or treatment of a potentially impairing illness or other condition does not necessarily imply impairment. This American College of Physicians position paper examines the professional duties and principles that should guide the response of colleagues and the profession to physician impairment. The physician should be rehabilitated and reintegrated into medical practice whenever possible without compromising patient safety. At the same time, physicians have a duty to seek help when they are unable to provide safe care. When identifying and assisting colleagues who might be impaired, physicians should act on collegial concern as well as ethical and legal guidelines that require reporting of behavior that puts patients at risk. Health care institutions and the profession should support practice environments in which patient safety is prioritized and physician wellness and well-being are addressed. Physician health programs should be committed to best practices that safeguard patient safety and the rights of physician-patients.