A fully comparative approach to what it meant to establish, live in or contest a frontier or border zone, as shown by the societies of late Antiquity and the Middle Ages, can help build a new shared understanding of the processes at work where borders are laid down or transgressed. The project Rethinking the Medieval Frontier has been exploring such ideas since 2015. Its first one-day conference, made possible by a British Academy/Leverhulme Trust Small ResearchGrant, will take place on 10th April 2018.