This review provides an overview of the concepts, methods and current status of the development of the Eleventh Revision of the Mental and Behavioural Disorders chapter of the International Classification of Diseases and Related Health Problems (ICD-11) by the World Health Organization (WHO). Given the global use of the current version (ICD-10) for a wide range of applications in clinical practice and health statistics, a major aim of the development process for ICD-11 has been to increase the utility of the classification system. Expert working groups with responsibility for specific disorder groupings first suggested a set of revised diagnostic guidelines. Then surveys were performed to obtain suggestions for revisions from practicing health professionals. A completely revised structure for the classification of mental and behavioural disorders was developed and major revisions were suggested, for example, for schizophrenia and other primary psychotic disorders, substance use disorders, affective disorders and personality disorders. A new category of “gaming disorder“ has been proposed and conditions related to sexual health and gender identity will be classified separately from mental disorders. An ICD-11 beta draft is freely available on the internet and public comments are invited. Field studies of the revised diagnostic guidelines are in process to obtain additional information about necessary improvements. A tabulated crosswalk from previous ICD-10 to then ICD-11 criteria will be necessary to ascertain the continuity of diagnoses for epidemiological and other statistical purposes. The final version of ICD-11 is currently scheduled for release by the World Health Assembly in 2018.