Both the practice of medicine and the expectations of patients regarding their care are changing. A point of confluence is in the need for medicine to be more patient centered and in the need for patients to be more involved in their care. This confluence is particularly pertinent when more than one reasonable approach is available to manage the patient's situation and when those approaches differ in ways that matter to patients. In shared decision making (SDM), clinicians and patients work together to understand the patient's situation and to determine how best to address it. Emergency medicine is not exempt from these trends. In this paper we seek to define SDM and its role in contemporary healthcare. Our goal is to set the stage for the active exploration of SDM in the care of patients in the emergency department (ED).