Existential therapy has been applied and continues to be applied in many forms and situations worldwide. However, until now, it lacked a coherent structure, analysis of its principles, and evaluation of its usefulness. Irvin Yalom, whose work "The Theory and Practice of Group Psychotherapy" has provided significant service in this dimension since 1970, provides existential psychotherapy with a foundation, synthesis, and framework. Organized around the four ultimate concerns of life—death, freedom, existential isolation, and meaninglessness—the book examines the meaning of each existential concern and the type of conflict that arises from confronting them. It shows how these concerns manifest in personality and psychopathology, and how therapy can be supported by our knowledge of them. Drawing from clinical experience, empirical research, philosophy, and great literature, Yalom has written an extensive and comprehensive work. It will offer an intellectual foundation to those psychotherapists who have perceived the incompatibility of orthodox theories with their clinical experience, opening new doors for empirical research. The fundamental concerns of therapy and the central issues of human existence are combined here as never before, with intellectual and clinical outcomes that will surprise and enlighten all readers.