This article advances transdisciplinarity as a potentially useful applied theatre theory and method. It maps the ways transdisciplinary research principles informed and framed an applied theatre project and suggests that making applied theatre explicit rather than implicit as a transdisciplinary research process may help practitioners conceptualise and manage projects. In our case, it also increased our ability to contribute to second-order (systemic) change. I argue that applied theatre was always-already transdisciplinary research but articulating this alignment may be helpful to both practice and analysis. The project presented here implemented applied theatre in a university-community partnership addressing youth justice.