The new edition of The American Psychiatric Association Publishing Textbook of Mood Disorders shares a title with the previous edition, but little else. Three of the four editors are new to the volume, as are three of every four contributors, and this new team has created an authoritative, comprehensive, and evidence-based book that captures cutting-edge thinking on the epidemiology, pathogenesis, treatment, and management of mood disorders. Indeed, much has changed in the study and practice around mood disorders in the 16 years since the first edition. For example, reflecting growth in the field of psychoneuroimmunology, the book reviews the latest research on the role of the immune system in mood disorders. In addition, epigenetics—which is proving useful in understanding depression and bipolar disorder—is explored, giving psychiatrists and other mental health care providers the knowledge, they need to stay abreast of advances. While the book's logical structure has been retained, each informative chapter offers fresh perspectives that rejuvenate and revivify the classic text. The second edition of The American Psychiatric Association Publishing Textbook of Mood Disorders is a book for a new generation of clinicians, trainees, and educators, and one that will earn its place next to other foundational, and indispensable, volumes.