Freedom of the will is not only an issue in the attribution of moral and legal responsibility—it also fundamentally shapes how we look at ourselves and how we interact with others. This is essential in everyday life but even more so in psychotherapy. In the debate on freedom of will, the main controversy is concerned with the relationship between determinism and free will. In this chapter, different positions are presented and discussed. The compatibilist viewpoint, which claims determinism and freedom of will to be compatible, is defended against competing theories and applied to psychotherapeutic work. Mental disorders affect free will in many ways, as is demonstrated by the examples. Nevertheless, a compatibilist approach to free will can be used as a resource to increase the patient’s autonomy. As a result, it is justified and sometimes appropriate within the therapeutic context to ascribe responsibility and, within certain limits, to express blame.