“Be the change” (BTC) was the theme for Cheltenham Science Festival. BTC set out to empower audiences as individuals and as a collective to enact positive change across a wide range of global issues linked to the UN Sustainable Development Goals. We examine the role of theming within festivals and analyse how BTC centred social change within the science festival. We conclude by noting that science festivals do not have to have science, technology, engineering or maths (STEM) themes, but can instead be themed around global social issues.