The use of social media has now become embedded in higher education and the work of academics. As social media potentially allows academics to engage with a wider range of audiences outside the academy, the opportunity to enhance the impact of research is often cited as a key part of the rationale for engaging with social media in this context. In this paper, we draw upon an online database of ‘impact case studies’ produced for the most recent national research audit in the UK – the ‘Research Excellence Framework’ – in 2021. We examine how and why social media is being referred to in this context, and the extent to which this has changed over time, by drawing comparisons with the previous exercise in 2014. Social media is mentioned to a much greater extent, featuring in 46% of case studies in 2021 compared to 25% in 2014. We also examine the database in terms of the particular platforms referred to, disciplinary differences, and ‘types’ of impact associated with social media. To conclude, we discuss the implications of the findings and areas for future research.