This article describes the current revision by the World Health Organization (WHO) of the International Classification of Diseases and Related Health Problems (ICD-10). ICD-10 is the basis for ICD-10-CM, which will be introduced in 2013 as the official U.S. system. U.S. psychologists will be required to use ICD-10-CM for all third-party billing and reporting, but are generally not familiar with the ICD or WHO’s role in global health classification. Although the U.S. lags behind other countries on the implementation of WHO’s international classification systems, psychologists and other health professionals will be affected by ICD-11, so it is important to understand its development. WHO views the current revision as an important opportunity to improve the clinical utility of the classification system for mental disorders. Serious problems with the clinical utility of both the ICD and the DSM are widely acknowledged. Clinical utility affects the daily lives of practitioners and is also a global public health issue. Most people with mental disorders worldwide receive no treatment. A diagnostic system with greater clinical utility can be a tool to improve identification and treatment, helping WHO member countries to reduce the disease burden of mental disorders. Consistent with this goal, WHO’s revision process is global, multilingual, and multidisciplinary and will produce different versions of the classification for clinical use, research, and primary care. A systematic program of studies being undertaken by WHO aimed at improving clinical utility is described. (PsycINFO Database Record (c) 2010 APA, all rights reserved)