The pursuit of greater research ‘impact’ has become embedded within Higher Education, through links to perceived value for money, and reified through institutional auditing processes. Academics are frequently encouraged to use social media as a means to facilitate public engagement and enhance research impact, as it offers the potential to connect with more diverse, non-academic audiences, and may lead to practical application of research findings. However, while social media training sessions are now common for academics and doctoral students, little is known about the relationship between use of social media and academics’ own perceptions of research impact and public engagement in practice. In this paper, findings are presented from text responses within a survey of academics (n=107) exploring examples of what they consider to be indicative of research impact through social media. This includes what academics perceive to be examples of high-impact interactions through social media, and how this is mediated by different platforms. The findings have practical implications for social media training for academics, and also suggest that institutional definitions of research impact may not account for the range of scholarly engagement social media platforms can facilitate.