This book explores the purpose of clinical psychological and psychiatric diagnosis, and provides a persuasive case for moving away from the traditional practice of psychiatric classification. It discusses the validity and reliability of classification-based approaches to clinical diagnosis, and frames them in their broader historical and societal context. The Diagnostic and Statistical Manual of Mental Disorders (DSM) is used across the world in research and a range of mental health settings; here, Stijn Vanheule argues that the diagnostic reliability of the DSM is overrated, built on a limited biomedical approach to mental disorders that neglects context, and ultimately breeds stigma. The book subsequently makes a passionate plea for a more detailed approach to the study of mental suffering by means of case formulation. Starting from literature on qualitative research the author makes clear how to guarantee the quality of clinical case formulations.