The International Statistical Classification of Diseases and Related Health Problems (ICD) is the most widely used medical terminology in the world. When the World Health Organization (WHO) started the development of the most recent version of ICD, the 11^th Revision, in 2007, it recognized that the development and the continuing maintenance of ICD-11 is a social process that must be supported by organizational and informatics infrastructures. In this presentation, I will outline the informatics infrastructure that was developed to support the world-wide collaboration of experts to develop and maintain ICD-11 and how the infrastructure has been extended to incorporate other WHO classifications.