The author shows how drama therapy draws on both drama and ritual. He argues that personal construct theory provides a hermeneutically useful approach to the study of drama therapy. He shows that drama therapy itself is an effective treatment for depression and schizophrenia, having a measurable effect on thought disorder; he thus tries to be as definite as possible about a subject which resists the 'scientific' apporach, and he is concerned not only to think rationally about drama therapy, but to examine the specific relationship between rational thought and artistic experience which allows the second to act as the mediator of the first. In Part One, the author investigates the therapeutic origins of theatre before moving on to the part played by drama in psychological maturation, leading to a discussion of depression, thought disorder and schizophrenia and the role of drama therapy in their treatment. Part Two examines the drama therapy experience and the ways in which the therapeutic possiblities of drama can be harnessed, both in improvised dramatic episodes and in theatre games, to achieve a wide range of therapeutic goals.