The International Classification of Diseases (ICD) is developed and maintained by the World Health Organization (WHO). The Eleventh Revision of the ICD (ICD-11) took effect in January 2022 and is the first major revision of the classification in 30 years. The ICD-11 reflects huge advances during this time in scientific evidence, clinical practices, and health information systems. The ICD is used for the classification and reporting of all types of diseases, disorders, and health conditions. This chapter focuses specifically on the ICD-11 classification of Mental, Behavioral or Neurodevelopmental Disorders (MBND). It covers the overall context of the development and metastructure of the MBND classification as well as the priorities and components of the Clinical Descriptions and Diagnostic Requirements (CDDR). The chapter considers what is new in ICD-11 MBND (e.g., the lifespan and dimensional approach, new disorders or removal of categories, coding issues). ICD-11 in the global reform of mental health and care and the role of national European and international professional organizations in education and training of ICD-11 MBND for improving quality treatment and care are constituent parts of this chapter.