With rapid urbanisation and a need for greater infrastructural resources to accommodate increasing influxes of people, cities have had to respond by been becoming ‘smarter’. One way of doing that is by developing the sharing economy, which is a mainly digitally enabled model for sharing idle assets and collaborating. While this solution is seen by some as part of a seamless, interconnected and frictionless future, alternative views suggest that smart cities need to make room for messiness, inefficiency and incoherence; this includes sharing that is ‘not smart’. Based on this premise, we ask the question: by being ‘smart’, what aspects of sharing are cities missing out on? This chapter begins by defining terms, such as ‘sharing’ and ‘sharing cities’, and makes the connection to ‘smart’. We then introduce a piece of research – workshops with local sharing experts – from the UK Engineering and Physical Sciences Research Council-funded Liveable Cities project in which we discuss what is missing from debates about sharing in smart cities. We conclude by arguing for the importance of what smart cities are missing: different forms of infrastructures to enable sharing practices that are both ‘smart’ and ‘non-smart’.