At the beginning of the long eighteenth century, the adjective 'British' primarily meant Welsh, in a narrow and exclusive sense. As the nation and the empire expanded, so too did Britishness come to name a far more diffuse identity. In parallel with this transformation, writers sought to invent a new British literary tradition. Timothy Heimlich demonstrates that these developments were more interrelated than scholars have yet realized, revealing how Wales was both integral to and elided from Britishness at the same historical moment that it was becoming a vitally important cultural category. Critically re-examining the role of nationalism in the development of colonized identities and complicating the core-periphery binary, he sheds new light on longstanding critical debates about internal colonialism and its relationship to the project of empire-building abroad.