The Tenth Revision of the International Classification of Diseases and Related Health Problems (ICD-10) includes a detailed classification of over 300 mental and behavioural disorders, which will become available in several different versions for different purposes. This version provides clinical descriptions of the disorders, and comprehensive guidelines for their diagnosis. Its publication follows extensive field-testing by more than 100 clinical and research centres in 40 countries. Clinical descriptions detail the principal signs and symptoms of each disorder, together with other important but less specific associated features. Diagnostic guidelines deal with the variety, balance, and – where appropriate – duration of symptoms that are the criteria for confident diagnoses. For many disorders, a short paragraph provides guidance on differentiation from other, confusingly similar, disorders. Where it is important to define the disorders that are either included or excluded by a particular category, these are clearly listed. The book has a full alphabetical index, and an annex lists other disorders covered by ICD-10 that may frequently occur in association with mental and behavioural disorders. The enormous amount of research and consultation that preceded publication has ensured that this book represents, as far as possible, all the major traditions and schools of psychiatry. Its uniquely international character will make it valuable in numerous contexts worldwide.