Thesis abstract: The current vogue for experiential performance in contemporary theatre has led to a rise in interactive, immersive and participatory approaches that focus on creating work that attempts to involve and respond to the audience as individuals. This development has in turn led to an interrogation and redefinition of aesthetics, for instance in Claire Bishop's Artificial Hells (2012), which examines spectatorship in participatory art. This thesis examines the aesthetics and ethics of participatory performance and argues that agency is fundamental to both. The research builds on Gareth White's Audience Participation in Theatre: Aesthetics of the Invitation (2013) and develops the discourse on participation by proposing a contextual understanding of agency that differentiates between the act and the experience of it. 
 
 The main research question of this thesis is: How does participatory performance operate as an aesthetic form? The thesis also examines how participation implicates ethics and the way that agency becomes both an aesthetic and ethical concern. In answering the main research question, the thesis also considers ways to analyse and evaluate participatory performance that take into consideration the different contexts of the participant's (inside) experience and (outside) observation of their decisions and contributions. 
 
 This research has taken a mixed-methods approach to enable a comprehensive response to the research question and employs audience research (implemented on three case studies) and practice-based research. Alongside these, the thesis draws on enactive and embodied cognition (Johnson, 2007; Gallagher and Zahavi, 2008; Fuchs and De Jaegher, 2009) to provide a nuanced perspective on agency, intersubjectivity and experience. The aesthetics of participation, and model for the analysis of participatory performance, I propose in this thesis focus on four key aesthetic elements: the intersubjective relationships between performer and participant (as well as between participants); the participant's embodied experience of doing within the performance; the creative contribution they make; and the demand characteristics of being a participant.