Overdiagnosis and overtreatment are increasingly being recognised as a significant problem in contemporary healthcare but are yet to receive any significant sociological attention. Overdiagnosis and overtreatment occur when a diagnosis is ‘correct’ according to current standards but the diagnosis or associated treatment has a low probability of benefitting the patient, and may instead be harmful. There are now numerous resources and tools available that seek to facilitate decision making and support patients and professionals to become comfortable with doing less rather than more. As an example, the Choosing Wisely campaign provides lists of interventions that may be unnecessary and seeks to support patients to ask questions of professionals about the necessity of these. As yet though scant attention has been paid to the ‘risk work’ that such initiatives create for health professionals. Taking decision making about population-based screening as an example, this paper will explore the work professionals do in order to attempt to navigate the risks and uncertainties of screening for both themselves and their patients. While participation in screening is increasingly being framed in terms of informed choice and emphasis is being placed on decision aids and shared decision making, evidence shows that professionals lack confidence and guidance on how to support patients to make decisions, feel uncertain of the evidence about harms and benefits of screening, lack external triggers to prompt meaningful engagement with patients, and, importantly, are concerned about being held accountable for decisions. Examination of the interactional work at the ‘sharp end’ of screening offers important insights into the way in which this form of work gets done by professionals and is experienced by patients, including problematizing ideals of non-directive counselling and the challenges of working with ambiguous or contested knowledges about risk and uncertainty.