This book was published in 1974 as a guide to a method of partially standardising the assessment of a subject's mental state with the object of achieving greater comparability between different examiners. The basis of the technique is a glossary of definitions of symptoms which is firmly grounded in the European school of psychiatry, with its long tradition of clinical observation and emphasis on the importance of listening to the a patient's description of unusual experiences. The definitions clearly set out the experiences which constitute psychiatric symptoms. An interview technique - the Present State Examination - which allows the symptoms to be elicited and reliably recorded is descried. The system was developed over a period of a decade and was still evolving at the time of this book's publication. The importance of this book lies in the fact that it shows how much the subjective element of psychiatric diagnosis may be brought under control.