The Theatrical Orchestra analyses experimental performances by British music ensembles in the twenty-first century. Orchestras are reconceiving how concerts are programmed and presented, how musicians perform, where performance can occur, and the role of the audience in the co-creation of the live event. They are embracing theatricality, thereby realising music more fully as a multi-sensory performance art. This book explains how and why orchestras are thinking theatrically about performance, and uses the work of British music ensembles as exemplars. It analyses performances by Aurora Orchestra, London Contemporary Orchestra, London Sinfonietta, Manchester Collective, Multi-Story Orchestra, Paraorchestra, Scottish Ensemble, and Southbank Sinfonia. The book bridges musicology and theatre studies to analyse the theatrical orchestra on the concert stage and beyond, addressing such topics as visuality, storytelling, physical performance, site-engaged performance, and immersive performance.