The year 1994 marks the twentieth anniversary of the original publication of Theatre of the Oppressed, the now well-known polemic in which Brazilian theatre activist Augusto Boal both analyzes western aesthetic philosophy since Aristotle and explicates his own system of political theatre. Influenced by Paulo Freire’s dialogic philosophy of education (Pedagogy of the Oppressed 1970), Boal’s vision is embodied in dramatic techniques that activate passive spectators to become spect-actors-engaged participants rehearsing strategies for personal and social change. Although founded in theatr ical exploration, the techniques, all based on transitive learning and collective empowerment, are not limited to the stage; educators, political activists, therapists, and social workers devoted to critical thought and action have adapted the work to address issues ranging from racism and sexism to loneliness and political impotence. Having won acclaim for its social relevance and adaptability, the work has entered global circulation as a composite system known as Theatre of the Oppressed (TO).