This chapter introduces the concept of internationalization in relation to theatre, using a wide range of historical and contemporary examples from around the world. It frames internationalization as a process – a set of interlocking real and perceived international flows of influence, practices, people, funds, and works – that is most effectively approached through examples of practice. Conceiving of theatre as a gathering of specific bodies in specific times and spaces engaged in specific tasks, all governed to some degree by state-based legal systems, the chapter differentiates itself from discussions of the transnational that focus on aspects that overcome state differences, instead using ‘internationalization’ as a term that aims to keep in mind the role of the state (for good or for ill, and whether nation-state or otherwise) in theatre. Following a discussion of the historical and contemporary effects of internationalization on theatre, a section on theatre and internationalization as discourse and politics explores theatre as a tool of ‘soft power’. An analysis of the megamusical then demonstrates how one might critique aspects of theatre in terms of globalization, while also picking out what it is doing positively, negatively, or simply differently in terms of internationalization.