Aspects of mental illness are still a mystery. Answers to the most important questions in psychiatry may require decades of further research, so it is important to critique contemporary practice a especially as fads in psychiatry have occurred not only on the fringe, but in the very mainstream of theory and practice. Some of the trendiest theoretical paradigms may turn out to be unsupported by data. In diagnosis, some faddish approaches to classification are unlikely to last. In treatment, both psychopharmacology and psychotherapy sometimes embrace interventions with a weak base in evidence that run the risk of doing harm to patients. This book examines fads and fallacies, both past and present, that plague psychiatry, both in diagnosis and in treatment. These include overdiagnosis (especially of depression, bipolar disorder, ADHD, PTSD and autism), overtreatment with pharmaceuticals and the assumption that neuroscience has all the answers. Until we really understand the nature of serious mental illness, psychiatrists need to resist fads in diagnosis and treatment. The best antidote lies in cautious conservatism and the principles of evidence-based practice