The phrase immersive theatre has experienced a surge in popularity in recent years, and is often applied loosely. In 2012 (‘theatre roundup: advice for playwrights’) Lyn Gardner noted that ‘immersive is theatre’s new buzzword’ and expressed irritation with its often vague and unspecific application, commenting on ‘marketeers who seem to be applying the term “immersive” to practically anything that isn’t a play by David Hare.’ A specialised vocabulary and set of critical approaches are required. This thesis is about audience immersion in the work of Punchdrunk, a pioneering company working in the form. The thesis proposes that immersive theatre (the theatrical form) and immersive experience (the sensation) have a reciprocal relationship. The thesis begins with an overview of approaches to audience in theatre scholarship and other fields, and establishes a definition of immersive experience that will be applied to case studies in the chapters. The thesis is divided into three sections that consider topics integral to Punchdrunk’s theatre: interactive elements; a fractured and nonlinear approach to narrative; and the creation of scenographically rich environments. The chapters consider the relationship between these topics and immersive experience. The thesis is interested in how immersive experience is created and maintained, and discussed and framed in wider discourse. The first section is about interactivity and immersion. Chapter 1 considers various approaches to interactivity and proposes a multivalent model. Chapter 2 applies this model to a discussion of interactivity and immersive experience in The Drowned Man. Chapter 3 widens the definition of interactivity to consider audience engagement beyond the moment of the theatrical encounter. The second section is about narrative and immersion. Chapter 4 outlines current critical approaches to narrative, and discusses immersion in the interplay of story structure and theatrical structure, using the linear The Crash of the Elysium as a case study. Following on from this, Chapter 5 considers how immersive experience is created and maintained in the context of a Punchdrunk trademark: a nonlinear structure, with scenes in non-chronological order encountered only when a wandering spectator comes across them. Chapter 6 draws on the narrative ‘vs’ ludology debate in the field of gaming; a debate concerned with what a player is actually immersed in – the story or the mechanics of play. The chapter considers immersive experience and story in the Sleep No More project Punchdrunk undertook with MIT Media Lab in 2012, which used gaming mechanics to explore ‘remote and real world interconnected theatrical immersion’. The final section is about environment and immersion. Chapter 7 outlines approaches to environment and draws on methodological approaches from site-specific performance to discuss how immersive experience manifests in the interplay between the original site and the creation of a fictional world in/on that site.