The International Society for Knowledge Organization, or ISKO, is a professional association for scholars of knowledge organization, knowledge structures, classification studies, and information organization and structure.

The Society publishes the academic journal Knowledge Organization as the official bi-monthly journal of ISKO. Founded in 1973 by Dr. Ingetraut Dahlberg, the first President of ISKO, it began publication the following year under the banner International Classification. In 1993 the title was changed to its present form. The journal publishes original research articles relating to general ordering theory, philosophical foundations of knowledge and its artifacts, theoretical bases of classification, data analysis and reduction. It also describes practical operations associated with indexing and classification. In addition to being a technical resource, the journal traces the history of knowledge organization and discusses questions of education and training in classification.

ISKO officially recognizes regional chapters in Brazil, Canada and the United States, China, France, Germany (including Austria and Switzerland), India, Italy, Maghreb (including Tunisia + Algeria + Morocco), Poland, Singapore, Spain (including Portugal), the United Kingdom, and West Africa. ISKO cooperates with international and national organizations such as UNESCO, the European Commission, the International Organization for Standardization, the International Federation of Library Associations and Institutions, the Association for Information Science and Technology, the Networked Knowledge Organization Systems/Services, and the International Information Centre for Terminology.