The thesis investigates the field of Theatre practice variously referred to as alternative, non-mainstream, avant-garde, community or fringe theatre. I have suggested the term 'Radical Group Theatre' - a term which, I believe, best encompasses the sector formerly represented by this diverse body of theatre practice. I focus on the relationship between theoretical and practical paradigms, and debates surrounding them; theatre making processes; and directorial practice in a theatre form which has emerged as a distinctive set of characteristics, ideological frameworks and practices in the Australian context. The work is strongly informed by the perspectives and practices of a range of major contributors to the field. It notes the inadequacy of conventional analytics and established understandings of the theory/practice nexus for exploring Radical Group Theatre, and establishes an alternate set of frameworks. These enable fresh engagement with the development and current praxis of an important theatre form which has not previously been considered as a whole field yet has taken particularly exciting directions in Australia over the past three decades. Methodology and objectives: An important aspect of the study is the way in which the research methodology parallels the practice under investigation. That is, the practice of Radical Group Theatre in Australia mirrors the 'Reflective Reflexive Loop' which I propose as the pre-eminent principle of the praxis. The methodology has developed out of my Masters degree research which was an interrogation of my directorial practice in the field of Youth/Community theatre, 1976-1989. I was further interested to analyse the field of group theatre to determine whether common key principles identified as characteristics of the form in the earlier study constituted the basis for an analytical model of Radical Group Theatre praxis. The investigation for this thesis began with a project designed to synthesise the essential qualities of directorial practice: the qualities of the good director, the major influences on practice, and the expectations participants have regarding the function of the director. The preliminary findings formed the basis for a comparative study which sought answers to the key questions as they apply to a pre-professional radical theatre setting - university student theatre. This project gave birth to the focus questions of the study which established the theoretical and methodological frames for the thesis.