The birth of permanent, secular, and popular theater in sixteenth and seventeenth century Europe gave rise to some of the most famous names in western literature, including Moliére, Lope de Vega, and Shakespeare. For centuries, early modern playwrights have been celebrated as cultural heroes in their respective homelands, but their status as 'national' figures--intimately connected to a specific linguistic heritage--belies the fact that the creation, performance, and publication of their enduring works took place within a complex network of transnational and translingual exchange. Western European theater in the sixteenth and seventeenth centuries was driven by the movement of texts, people, practices, and ideas between the stages of London, Madrid, and Paris. The theatrical practices that emerged in these capitals arose out of regional trends in demographics, urban social organization, the consolidation of monarchical authority, print culture, trade, travel, and nascent nationalism. As a result, these practices shared not only obvious similarities, but also systems of mutual influence. Notably, the dramatic content appearing on Europe's urban stages reflected persistent patterns of acknowledged and unacknowledged translation, adaptation, and appropriation that contradict traditional assumptions of stable national literary canons. The widespread borrowing of plots, themes, and even entire scripts across geopolitical boundaries generated a dialogue of intense competition between the various European theater capitals and their representative playwrights in attempts to locate and segregate authentic national identities. These debates--compounded by significant cross-cultural currents in staging, scenery, properties, music, and dance--reveal that the early modern theater, both as physical space and creative act, became a place where individuals and groups experienced and made sense of the relationship between the familiar and the foreign. This dissertation explores the entwined histories of performance, publication, commodities exchange, human migration, and cultural identity to illustrate the manifold ways in which theater provided the people of early modern Europe with a window onto the wider world.