In this thesis I present a new dramaturgical model for understand improvised theatre. Improvised theatre is a field full of experimentation, and the art form has recently been evolving faster than the theories used to understand it. Rather than relying on colloqiual terms such as “short form” and “long form”, I propose a new terminilogy based on Chris Johnston’s notion of “Restrictions”. I explain the use of the Restrictions: Location, Role, Narrative, Game, and Materials, and how to meassure the “Scope” of Restrictions by the Number of affected performers and Duration. I explain how Restrictions affect four elements of improvised performance: Space, Time, Speech, and Physicality. By creating a rubric to illustrate the interaction between Restrictions and these elements, I move towards a new foundation for understanding improvised theatre. In addition, I propose four metrics to meassure audience participation: Number of participants, Method of participation, Agency of the participat, and Duration of the participation. Using my Restriction rubric and audience participation metrics, I analyse four case studies. Each case study is a recent piece of improvised theatre. I attended each piece multiple times and interviewed the artists behind eacch production with a questionnaire. These are Blind Date and Undercover by Spontaneous Theatre, Quest Friends Forever, and GRIMprov’s Guided Roleplay. Each production features audience participation, the effects of which I explain using Erika Fischer-Lichte’s notion of the autopoietic feedback loop.By analysing these contemporary productions I demostrate the efficacy of my new rubrics and terminilogy.