Over the past decade, historians, journals, conferences, and even job advertisements have devoted attention to a new field of inquiry, “Britain and the world.” This emergent category is far from coherent but, despite a variety of approaches, shares a common assumption that Britain's interactions with the world beyond its shores enable us to better understand the histories of both Britain and the globe. Writing the history of Britain from a comparative, imperial, or transnational perspective is not wholly new. British historians have long worked comparatively in a predominantly European frame, while historians of empire and internationalism have also highlighted the importance of transnational and global frameworks. What, then, is signified by the articulation of “Britain and the world” as a new field? What do historians of Britain, and indeed historians of its empire and the world, stand to gain or lose from the promotion of Britain and the world as a field? What new skills, methodologies, and archives are required to become a historian of Britain and the world? We invited historians from different generations and national academies as well as with different ways of approaching the history of Britain in an extranational frame. Our hope is that these essays will open up debate and stimulate broader discussions about the changing nature of the field and our work as historians of Britain.