Depression is a widespread and quite severe mental disorder. The incidence of depression is steadily increasing worldwide, especially in developed countries. This book describes a relatively new way of treating depression - acceptance and commitment therapy (ACT). The program described in the book and supported by the results of numerous studies introduces the ACT model at both theoretical and practical levels. This book, written by one of the first researchers on the effectiveness of ACT in treating depression, will be a valuable resource for working with clients suffering from depression.