The seven articles in this special issue were selected from those delivered at a series of workshops undertaken by the European Commission H2020-funded Building Resilience Against Violent Extremism (BRaVE) Project in 2020–2021. Understanding polarization and (violent) extremism as distinct, interlinked, phenomena, the collected articles ask how online platforms can be mobilised to disrupt and reframe ideologies underpinning polarising and extremist messaging. To what extent can social media platforms serve as critical resources that contribute to building pro-social resilience? And, how can we build on what has been effective so far in terms of building online resilience, including what else might social media platforms and their users do to enhance what has already been found to be effective?