The book covers the subject of existential theatre in the biographical experiences of adults from the perspective of experiencing existential disability. It is an attempt to open a discussion about the place of theatre in the space of pedagogy and andragogy, as well as an invitation to look for inspiration to build stories about human experience outside the field of social research. The author focuses on recognising theatre as one of the forms of adult education from a biographical perspective; presents the activities of non-professional adult theatres and explores theatre experiences in terms of shaping strategies for coping with existential disability. The work presents a network of key categories that make up the author's concept of existential theatre, and also indicate the direction of thinking and action in the space of pedagogical and andragogic theatre activities. The author also considers the fundamental question about the tension between art and therapy in educational and artistic activities, and emphasises significant threats in popular theatre practice.