Between the turn of the twentieth century and the outbreak of the Second World War, avant-garde theatre artists challenged traditional norms through experimentation and radical innovation. Blurring the boundaries separating drama, theatre, and performance, these artists employed deliberate provocations and welcomed the audience’s displeasure. In subject matter, the theatrical avant-garde was equally pathbreaking, addressing a number of issues crucial to early twentieth-century modernity: war and revolution, gender roles, technology, rationality and the subconscious, futurity and the new, and the role of art in a rapidly transforming world. Futurism, Dadaism, and surrealism – three of the leading avant-garde movements – incorporated new materials and activities; brought theatre into dialogue with cabaret, variety show performance, circus, and the art of declamation; and dramatically redefined the actor’s role. Their innovations inspired contemporary experiments in non-realist staging, environmental theatre, performance art, and immersive performance.