This publication – Supplying the Roman Empire – is the fourth volume of the LIMES XXV’s congress proceedings and deals with various aspects of the supply and provisioning of the Roman empire, and the role of the Roman armies housed on its fringes herein. The result is a wide-ranging collection of papers dealing with topics such as: finds of organic material; riverine and maritime supply and security; militarily controlled mining; building material procurement and processing; agro-political schemes and water management; military material culture. The proceedings are all arranged around the original sessions, trying to create coherent thematical collections that make the vast output more accessible to generalists and specialists alike.Frontiers are zones, or lines, of contact and coercion, of exchange and exclusion. As such they often express some of the most typical elements of the socio-political spaces that are defined by them. Spanning some 6,000 km along rivers, mountain ranges, artificial barriers and fringes of semi-desert, the frontiers of the Roman empire offer a wide variety of avenues and topics for a very diverse community of scholars. They are the central subject of the International Congress of Roman Frontier Studies (or just Limes Congress after the Latin word for ‘border’), organised every three years since 1949. This four-volume publication contains most of the papers presented at the 25th edition which was hosted by the municipality of Nijmegen in August 2022.