ICD is the acronym for the International Classification of Diseases, which is the diagnostic manual of the World Health Organization (WHO). The ICD includes all officially recognized illnesses and medical conditions—including a section on mental and behavioral disordersthat is important for mental health professionals. The current version is the ICD-10, which was published back in the early 1990s. As a member of the World Health Organization, the United States is required to use the ICD. However, even though ICD-10 came out more than two decades ago and has been in use in other WHO-member countries for a long time, the U.S. only switched from ICD-9 to ICD-10 in 2015.