The original edition of Klaus Grawe's book exploring the basis and need for a more generally valid concept of psychotherapy fueled a lively debate among psychotherapists and psychologists in German-speaking areas. Now available in English, this book will help spread the concepts and the debate among a wider audience. The book is written in dialog form. A practicing therapist, a research psychologist, and a therapy researcher take part in three dialogs, each of which builds on the results of the previous dialog. The first dialog explores how therapeutic change takes place, while the second looks at how the mechanisms of action of psychotherapy can be understood in terms of basic psychological concepts. Finally, in the third dialog, a psychological theory of psychotherapy is developed. The practical implications of this are clearly shown in the form of case examples, as well as guidance on indications and treatment planning. The dialog ends with suggestions as to how therapy training and provision of psychotherapy could be improved on the basis of the model of psychotherapy that has been developed.