There has been optimism that social media will facilitate citizen participation and transform the communication strategies of public organisations. Drawing on a case study of the public police in England, this article considers whether social media are transforming or normalising communications. Arguing that social media have not yet served to facilitate interaction between constabularies and citizens in the ways that have been proposed and desired, the article considers factors that structure the transformative potential of social media. It is argued that the uses of social media are mediated by the existing organisational and occupational concerns of the police. This article reveals how an interplay of organisational, technological and individual and cultural dynamics come together to shape how social media are used in constabularies. Embedding social media into police communications is challenging and the technology itself will not bring about the organisational and cultural changes needed to transform police–citizen engagement.