Shared decision making is a process in which patients are involved as active partners with the clinician in clarifying acceptable medical options and in choosing a preferred course of clinical care. Shared decision making offers a way of individualizing recommendations, according to patients' special needs and preferences, when some patients may benefit from an intervention but others may not. This paper clarifies how the U.S. Preventive Services Task Force (USPSTF) envisions the application of shared decision making in the execution of screening and chemoprevention. Unlike conventional USPSTF reports, this paper is neither a systematic review nor a formal recommendation. Instead, it is a concept paper that includes a commentary on the current thinking and evidence regarding shared decision making. Although the USPSTF does not endorse a specific style of decision making, it does encourage informed and joint decisions. This means that patients should be informed about preventive services before they are performed, and that the patient-clinician partnership is central to decision making. The USPSTF suggests that clinicians inform patients about preventive services for which there is clear evidence of net benefit, and, if time permits, about other services with high visibility or special individual importance. Clinicians should make sure that balanced, evidence-based information about the service (including the potential benefits and harms, alternatives, and uncertainties) is available to the patient if needed. For preventive services for which the balance of potential benefits and harms is a close call, or for which the evidence is insufficient to guide a decision for or against screening, clinicians should additionally assist patients in determining whether individual characteristics and personal preferences favor performing or not performing the preventive service. The USPSTF believes that clinicians generally have no obligation to initiate discussion about services that have either no benefit or net harm. Nonetheless, clinicians should be prepared to explain why these services are discouraged and should consider a proactive discussion for services with high visibility or special individual importance or for services for which new evidence has prompted withdrawal of previous recommendations.