Physicians have the opportunity to contribute to the betterment of public health more often than thay may know. This month's issue focuses on how physicians' every day clinical decisions affect the health of the public. Contributors examine clinical encounters in which physicians are faced with situations of public health concern such as patients who are being abused or struggling to tell partners about their HIV-positive status. How physicians' other ethical obligations, such as keeping patient-physician confidentiality, may conflict with their interests in protecting the public and with legal mandates is also explored. Physician choices, such as opting to practice concierge medicine or not considering cost-effectiveness in treatment decisions, may also affect public health by making health care less accessible and affordable.