In this article Erika Fischer-Lichte argues that, since the beginning of the twentieth century, in different parts of the world, modern theatre was invented by way of interweaving cultures in performance. Different examples from the early twentieth century and the 1990s show how theatre acted as a laboratory for testing and experiencing the potential of cultural diversity. An innovative performance aesthetics enabled the exploration of the emergence, stabilization, and destabilization of cultural identity, merging aesthetics with politics. Erika Fischer-Lichte is Professor of Theatre Studies at the Freie Universität in Berlin. She has published widely in the fields of the theory and history of the theatre, and is the author of numerous books, including, in English, Theatre, Sacrifice, Ritual: Exploring Forms of Political Theatre (2005) and The Transformative Power of Performance: a New Aesthetics (2008). In 2008 she established a new research programme, ‘Interweaving Cultures in Performance’, at the Freie Universität. This paper was given as a keynote lecture at the fourteenth Performance Studies International conference, ‘Interregnum: In Between States’, in Copenhagen, 20–24 August 2008.