Positive deviance is an asset-based improvement approach. At its core is the belief that solutions to problems already exist within communities, and that identifying, understanding, and sharing these solutions enables improvements at scale. Originating in the field of international public health in the 1960s, positive deviance is now, with some adaptations, seeing growing application in healthcare. We present examples of how positive deviance has been used to support healthcare improvement. We draw on an emerging view of safety, known as Safety II, to explain why positive deviance has drawn the interest of researchers and improvers alike. In doing so, we identify a set of fundamental values associated with the positive deviance approach and consider how far they align with current use. Throughout, we consider the untapped potential of the approach, reflect on its limitations, and offer insights into the possible challenges of using it in practice. This title is also available as Open Access on Cambridge Core.