This book contains, in addition to an introduction, sixteen chapters, each with its own introduction and discussion, that review various issues within psychiatric nosology from clinical, historical and particularly philosophical perspectives. The contributors to this book include major psychiatric researchers, clinicians, historians and especially nosologists (including several leaders of the DSM-5 effort and the DSM Steering Committee that will be guiding future revisions in DSM for the foreseeable future), psychologists with a special interest in psychiatric nosology and philosophers with a wide range of orientations. The book is organized into four major sections. The first explores the nature of psychiatric illness and the ways in which define it including clinical and psychometric perspectives. The second section examines problems in the reification of psychiatric diagnostic criteria, the problem of psychiatric epidemics and the nature and definition of individual symptoms. The third session explores the concept of epistemic iteration as a possible governing conceptual framework for the revision efforts for official psychiatric nosologies such as DSM and ICD and the problems of validation of psychiatric diagnoses. The final session explores how we might move from the descriptive to the etiologic in psychiatric diagnoses, the nature of progress in psychiatric research and the possible benefits of moving to a living document (or continuous improvement) model for psychiatric nosologic systems. The organization of the book—with its introduction and comments—well captures the dynamic cross-disciplinary interactions that characterize the best work in the philosophy of psychiatry.