The effects of mental disorder are apparent and pervasive, in suffering, loss of freedom and life opportunities, negative impacts on education, work satisfaction and productivity, complications in law, institutions of healthcare, and more. With a new edition of the 'bible' of psychiatric diagnosis - the DSM - under developmental, it is timely to take a step back and re-evalutate exactly how we diagnose and define mental disorder.This new book by Derek Bolton tackles the problems involved in the definition and boundaries of mental disorder. It addresses two main questions regarding mental illness. Firstly, what is the basis of the standards or norms by which we judge that a person has a mental disorder - that the person's mind is not working as it should, that their mental functioning is abnormal? Controversies about these questions have been dominated by the contrast between norms that are medical, scientific or natural, on the one hand, and social norms on the other. The norms that define mental disorder seem to belong to psychiatry, to be medical and scientific, but are they really social norms, hijacked and disguised by the medical profession?Secondly, what is the validity of the distinction between mental disorder and order, between abnormal and normal mental functioning? To what extent, notwithstanding appearances, does mental disorder involve meaningful reactions and problem-solving? These responses may be to normal problems of living, or to not so normal problems - to severe psycho-social challenges. Is there after all order in mental disorder?With the closing of asylums and the appearance of care in the community, mental disorder is now in our midst. While attempts have been made to define clearly a concept of mental disorder that is truly medical as opposed to social, there is increasing evidence that such a distinction is unviable - there is no clear line between what is normal in the population and what is abnormal. 'What is Mental Disorder?' reviews these various crucial developments and their profound impact for the concept and its boundaries in a provocative and timely book.