| IAF | Irish Arts Foundation | In English | → Foundations → Arts |
| IAF | Internationales Afrikaforum | In German | |
| IAF | International Apparel Federation | In English | |
| IAF | International Association of Facilitators | In English | → Associations |
| IAF | Inter-American Foundation | In English | → Foundations |
| IAF | Industrial Areas Foundation | In English | → Foundations → Industry, industrial policy |
| IAF | Interessengemeinschaft Ausbildung im Finanzbereich | In German | → Finance → Education |
| IAF | International Astronautical Federation | In English | → Spaceflight engineering, astronautics |
| IAF | International Aikido Federation | In English | → Entertainment |
| IAGC | Institute of Applied Genetics and Cell Biology = IAGZ | Institut für Angewandte Genetik und Zellbiologie | In German |
In English | → Research institutes → Genetics → Cytology |
| IAGZ | Institut für Angewandte Genetik und Zellbiologie = IAGC (look above) |
In German | → Research institutes → Genetics → Cytology |
| IAH | International Association of Hydrogeologists | In English | → Associations → 5325 → Hydrology |
| IAHA | International Association of Historians of Asia | In English | → Associations → History |
| IAHR | International Association of Hydraulic Engineering and Research | In English | → Associations → Environmental technology, water supply, waste management |
| IAHS | International Association of Hydraulical Sciences | In English | → Associations → Environmental technology, water supply, waste management |
| IAIN | International Association of the Navigation Institutes | In English | → Associations → Geodesy, cartography → Vehicle engineering |
| IAL | International Association for Lichenology | In English | → Botany |
| IALANA | International Association of Lawyers Against Nuclear Arms | In English | → Associations → Law, jurisprudence → Nuclear technology → Applied sciences, technology |
| IALS | International Association of Literary Semantics | In French | → Associations → Literature |
| IAM | International Association of Machinists | In English | → Associations → Mechanical engineering |
| IAO | Institut für Arbeitswirtschaft und Organisation (www.iao.fraunhofer.de) | In German | → Research institutes → Labour, labour economics |
| IAPO | International Alliance of Patients' Organizations (www.patientsorganizations.org) | In English | → Medicine |
| IAPS | International Association of Pastel Societies | In English | → Associations |
| IAPS | Independent Association of Prep Schools | In English | → Associations → Education |
| IAPS | International Association for the Philosophy of Sport | In English | → Associations → Philosophy, psychology → Sport, physical exercises |
| IAPS | International Association of Physics Students | In English | → Associations → Education → Physics |
| IAPS | International Association for People-environment Studies | In English | → Associations → Nature and society |
| IAPS | International Association of Patristics Studies = AIEP | Association Internationale des Études Patristiques | In French |
In English | → Associations → Archeology → Roman catholic church |
| IARC | International Agency for Research on Cancer | In English | → Oncology |
| IAS | International Association of Sufism | In English | → Associations → Islam |
| IAS | Islamic Academy of Sciences | In English | → Academies → Islam → Mathematics and natural sciences |
| IAS | Indian Academy of Science | In English | → Serial publications, periodicals → Academies → Mathematics and natural sciences |
| IASCF | International Accounting Standards Committee Foundation | In English | → Foundations → Standardization → Commercial law → Applied sciences, technology |
| IASON | In Aangename Samenwerking Overwinning Nastreven | In Dutch | → Sport, physical exercises |
| IASP | International Association of Science Parks | In English | → Associations → Museums → Mathematics and natural sciences |
| IASP | Indian Association for the Study of Population | In English | → Associations → Demography |
| IASPEI | International Association of Sesimology ans Physics of Earth Interior (www.iaspei.org) | In English | → Research institutes → Geophysics → Seismology, earthquakes |
| IASS | International Association for Semiotic Studies = AIS | Association Internationale de la Sémiotique | In French |
In English | → Associations → Semiotics |
| IASS | International Association of Sanskrit Studies | In English | → Associations → Language, linguistics, literature |
| IASSI | Indian Association of Social Science Institutions | In English | → Associations → Social sciences |
| IASTAM | International Association for the Study of Traditional Asian Medicine | In English | → Associations → 6158 |
| IAT | Institute of Animal Technology (www.iat.org.uk) | In English | → Pharmacology, toxicology → Veterinary medicine |
| IATA | International Air Transport Association | In English | → Associations → Transport and postal services |
| IATC | International Association of Teachers of Czech | In English | → Associations → Education → Language, linguistics, literature |
| IATIS | International Association for Translation and Intercultural Studies | In English | → Associations → Linguistics |
| IATSE | International Alliance of Theatrical Stage Employees and Moving Picture Machine Operators | In English | → Cinema, movies → Theatre |
| IATSS | International Association of Traffic and Safety Sciences | In English | → Associations → Transport and postal services |
| IAU | International Astronomical Union | In English | → Astronomy |
| IAUPL | Internacia Asocio de Universitataj Profesoroj kaj Lekciistoj | In Esperanto | → Associations → Higher education, universities |
| IAVCEI | International Association of Volcanology and Chemistry of the Earth's Interior (www.iavcei.org) | In English | → Associations → 55121 → Geochemistry |
| IB | Institut für Bodenforschung (www.boku.ac.at/boden/) | In German | → Research institutes → Agricultural sciences |
| IBA | Institute for Biomedical Aging Research | In English | → Research institutes → Biological sciences → Medicine |
| IBA | International Bar Association (www.ibanet.org) | In English | → Associations → Law, jurisprudence |
| IBAS | Indonesian Business Association of Shanghai | In English | → Associations → Economics |
| IBC | Itteren Borgharen Combinatie | In Dutch | → Sport, physical exercises |
| IBE | International Bureau for Epilepsy (www.ibe-epilepsy.org) | In English | → Neurology |
| IBEC | Irish Business and Employers Confederation | In English | → Labour, labour economics → Economic policy |
| IBEW | International Brotherhood of Electrical Workers | In English | → Electrical engineering |
| IBL | Institut de Biologie de Lille | In French | → Research institutes → Biological sciences |
| IBN | Institute of Bioengineering and Nanotechnology | In English | → Research institutes → Biotechnology |
| IBO | Associazione Italiana Soci Costruttori | In Italian | → Associations |
| IBT | Internationaler Bund der Tierversuchsgegner (www.tierversuchsgegner.at) | In German | → Nature → Pharmacology, toxicology |
| IBT | International Brotherhood of Teamsters | In English | |
| ÍBV | Íþróttabandalag Vestmannaeyja (www.ibv.is) | In Icelandic | → Sport, physical exercises |
| ICAAE | International Center for Aquaculture and Aquatic Environments | In English | → Fishing, hunting |
| ICAANE | International Congress on the Archaeology of the Ancient Near East | In English | → Congresses → Archeology |
| ICAD | International Conference on Auditory Display | In English | → Congresses → Human-computer interaction → Telecommunications |
| ICAD | International Conference on Alzheimer's Disease (and Related Disorders) | In English | → Congresses → Neurology |
| ICADTS | International Council on Alcohol and Traffic Safety | In French | → Medicine → Transport and postal services |
| ICAITI | Instituto Centroamericano de Investigación y Tecnología | In Spanish | → Research institutes → Research policy → Engineering, technology |
| ICAMES | Interuniversity Consortium for Arab and Middle Eastern Studies | In English | → Area studies |
| ICANAS | International Congress for Asian and Northern African Studies | In English | → Congresses → Area studies |
| ICANN | International Conference on Artificial Neural Networks | In English | → Congresses → Artificial intelligence |
| ICAO | International Civil Aviation Organization = IOCA | Internacia Organizo pri Civila Aviado | In Esperanto |
In English | → Aeronautics, aircraft → Transport and postal services |
| ICAP | International Conference on Atomic Physics | In English | → Congresses → 53198 |
| ICAP | Idaho Child Abuse Prevention (Coalition) (www.idahosheart.org) | In English | → Sexual problems → Law, jurisprudence |
| ICARDA | International Center for Agricultural Research in the Dry Areas | In English | → Research institutes → Agricultural sciences |
| ICAS | International Convention of Asia Scholars | In English | → Area studies |
| ICB | International Centre of Biocybernetics | In English | → Research institutes → Computer science → Electronics |
| ICC | International Association for Cereal Science and Technology | In English | → Associations → Agricultural sciences |
| ICC | Internet Chess Club | In English | |
| ICC | International Chamber of Commerce (www.iccwbo.org) = CCI | Cámara de Comercio Internacional | In Spanish = CCI | Chambre de Commerce Internationale | In French = CCI | Câmara de Comércio Internacional | In Portuguese |
In English | → Trade |
| ICCA | International Congress and Convention Association | In English | → Associations → Congresses |
| ICCHP | International Conference on Computers Helping People with Special Needs | In English | → Congresses → Computer-based techniques |
| ICCO | Interkerkelijke organisatie voor ontwikkelingssamenwerking | In Dutch | → Development |
| ICDAR | International Conference on Document Analysis and Recognition | In English | → Congresses → Document processing |
| ICEI | Istituto Cooperazione Economica Internazionale | In Italian | → International economic cooperation |
| ICEIS | International Conference on Enterprise Information Systems | In English | → Congresses → Knowledge management → Data |
| ICES | International Council for Exploration of the Sea | In French | → Earth sciences → Zoology |
| ICES | International Council for the Exploration of the Seas (www.ices.inst.dk) | In English | → Marine research, oceanography |
| ICF | International Canoe Federation (www.canoeicf.com) | In English | → Sport, physical exercises |
| ICF | International Coach Federation (www.coachfederation.org) | In English | → 659 |
| ICFTU | International Confederation of Free Trade Unions (www.icftu.org) = CISL | Confédération Internationale des Syndicats Libres | In French = CIOSL | Confederación Internacional de Organizaciones Sindicales Libres | In Spanish = CIOSL | Confederação Internacional de Organizações Sindicais Livres | In Portuguese = ICB | International Criminal Bar | In English = BPI | Barreau Pénal International | In French |
In English | → Labour, labour economics |
| ICHO | Iran Cultural Heritage Organisation | In English | → Civilization, culture, progress |
| ICHR | Indian Council for Historical Research | In English | → History |
| ICHRDD | International Centre for Human Rights and Democratic Development (www.ichrdd.ca) = CIDPDD | Centre International des Droits de la Personne et du Développement Démocratique | In French |
In English | → Fundamental rights → Democracy |
| ICHRP | International Council on Human Rights Policy | In English | → Fundamental rights |
| ICHSEA | International Conference on the History of Science in East Asia | In English | → Congresses → Mathematics and natural sciences → History |
| ICID | International Commission on Irrigation and Drainage | In English | → Agricultural sciences → Environmental technology, water supply, waste management |
| ICID | International Commission for Irrigation and Drainage = CIID | Commission Internationale pour les Irrigations et le Drainage | In French |
In English | → 627 → Agricultural sciences |
| ICLP | Institute of Chinese Literature and Philosophy | In English | → Research institutes → Philosophy, psychology → Literature |
| ICMI | International Commission on Mathematical Instruction (www.mathunion.org/ICMI/) | In English | → Mathematics → Education |
| ICMI | International Conference on Multimodal Interfaces | In English | → Congresses → Human-computer interaction |
| ICMS | International Committee on Museum Security | In English | → Museums |
| ICN | International Conference on Nutrition = CIN | Conferencia Internacional sobre Nutrición | In Spanish = CIN | Conférence Internationale sur la Nutrition | In French = CIN | Conferência Internacional sobre Nutrição | In Portuguese |
In English | → Congresses → Nutrition |
| ICOC | Indonesia Council Open Conference | In English | |
| ICOLD | International Commission on Large Dams (www.icold-cigb.org) | In English | → 627 |
| ICOPHIL | International Conference on Philippine Studies | In English | → Congresses → Area studies |
| ICORD | International Collaboration on Repair Discoveries | In English | → Neurology → Traumatology |
| ICOTT | International Congress of Official Tourist Traffic Associations | In English | → Tourism |
| ICPDR | International Commission for the Protection of the Danube River | In English | → Nature and society → 627 |
| ICPO | International Criminal Police Organization | In English | → Police |
| ICPO | Institute of Cytology & Preventive Oncology | In English | → Research institutes → Cytology → Oncology |
| ICPR | Indian Council of Philosophical Research | In English | → Philosophy, psychology |
| ICPS | International Conference on the Physics of Semiconductors | In English | → Congresses → Electricity, magnetism, electromagnetism → 539 → Electrical engineering |
| ICRA | Internet Content Rating Association | In English | → Internet |
| ICRA | Association de Classification du Contenu de l'Internet | In French | → Internet → Libraries → Associations |
| ICRAT | International Conference on Research in Air Transportation | In English | → Congresses → Transport and postal services |
| ICRC | International Committee of the Red Cross (www.icrc.org) = CICR | Comité Internacional de la Cruz Roja | In Spanish = CICR | Comité International de la Croix-Rouge | In French = CICV | Comitê Internacional da Cruz Vermelha | In Portuguese = МККК | Международный комитет Красного Креста | In Russian = SSKK | Starptautiskā Sarkanā Krusta Komiteja | In Latvian = CICR | Comitato Internazionale della Croce Rossa | In Italian = ICRC | 적십자 국제 위원회 | In Korean = CICR | Comitè Internacional de la Creu Roja | In Catalan = CICR | Comitât entèrnacionâl de la Crouèx-Roge | In Franco-Provençal |
In English | → Medicine |
| ICRC | 적십자 국제 위원회 (www.icrc.org) = CICR, CICV, МККК, SSKK (look above) |
In Korean | → Medicine |
| ICRISAT | International Crops Research Institute for the Semi-Arid Tropics | In English | → Agricultural sciences |
| ICS | International Child Support | In English | |
| ICS | International Commission on Stratigraphy | In English | → Stratigraphy |
| ICSA | International Cultic Studies Association | In English | → Associations → Social sciences |
| ICSC | International Council of Shopping Centers | In English | → Trade |
| ICSSR | Indian Council of Social Science Research | In English | → Social sciences |
| ICSU | International Council of Scientific Unions | In English | → Mathematics and natural sciences |
| ICSV | International Congress on Sound and Vibration | In English | → Congresses → Acoustics |
| ICTA | Instituts et Centres Techniques Agricoles | In French | → Research institutes → Agricultural sciences |
| ICTS | International Conference on Thai Studies | In English | → Congresses → Area studies |
| ICTU | Irish Congress of Trade Union | In English | → Labour, labour economics |
| ICTU | Irish Congress of Trade Unions | In English | → Labour, labour economics |
| ICU | Istituto per la Cooperazione Universitaria | In Italian | → Higher education, universities |
| ICUAER | International Commitee on Urgent Anthropological and Ethnological Research | In English | → Ethnology → Anthropology |
| ID | Initiative Développement | In French | → Development |
| IDA | International Development Association (www.worldbank.org/ida/) = AID | Association Internationale de Développement | In French = AIF | Asociación Internacional de Fomento | In Spanish = AID | Associação Internacional de Desenvolvimento | In Portuguese = МАР | Международная ассоциация развития | In Russian = MAP | Міжнародна асоціація розвитку | In Serbian |
In English | → Associations → Development |
| IDEO | Institut Dominicain d'Études Orientales du Caire | In French | → Research institutes → Roman catholic church → Area studies |
| IDF | International Diabetes Federation (www.idf.org) = FID | Fédération Internationale du Diabète | In French = FID | Federación Internacional de Diabetes | In Spanish |
In English | → Pathology |
| IDF | International Dairy Federation | In English | → Agricultural sciences → Food technology |
| IDM | Institut für den Donauraum und Mitteleuropa | In German | → Research institutes → International relations → Area studies |
| IDSA | Institute for Defense Studies and Analyses | In English | → Research institutes → Polemology → 355 |
| IEAS | Institute of East Asian Studies | In English | → Research institutes → Area studies |
| IEC | Independent Ethics Committee | In English | → Ethics |
| IEF | International Energy Foundation | In English | → Foundations → Energy economics |
| IEHS | Immigration and Ethnic History Society | In English | → Migrations → Sociology → History |
| IEJ | Itala Esperantista Junularo (http://iej.esperanto.it) | In Esperanto | → Associations |
| IEKA | Internacia Esperanto-Klubo Aŭtomobilista | In Esperanto | → Vehicle engineering → Transport and postal services |
| IEM | Internacia Esperanto-Muzeo | In Esperanto | → Museums → Artificial languages (linguistics) |
| IESG | Internet Engineering Steering Group | In English | → Internet |
| IEŚW | Instytut Europy Środkowo-Wschodniej | In Polish | → Research institutes |
| IETF | Internet Engineering Task Force | In English | → Networks, communication |
| IEV | In Eendracht Vooruit | In Dutch | → Sport, physical exercises |
| IEXAS | Institute of Experimental Animal Sciences | In English | → Veterinary medicine |
| IFAN | International Federation of Standards Users | In English | → Standardization |
| IFC | Idose Football Club | In Dutch | → Football and rugby |
| IFCAI | International Federation of Commercial Arbitration Institutions | In English | → Commercial law |
| IFDA | International Furnishings and Design Association | In English | → Associations → Drawing and applied arts |
| IFEAC | Institut Français d'Études sur l'Asie Centrale | In French | → Research institutes → Area studies |
| IFEAD | Institut Français d'Études Arabes de Damas | In French | → Research institutes → Language, linguistics, literature → Geography, biography, history |
| IFEF | Internacia Fervojista Esperanto Federacio | In Esperanto | → Rail transport engineering → Transport and postal services |
| IFEN | Institut Français de l'Environnement | In French | → Research institutes → Nature → Environment, environmental sciences |
| IFES | Institute of Far Eastern Studies | In English | → Research institutes → Area studies |
| IFIC | International Food Information Council | In English | → Nutrition → Food technology |
| IFIG | Internationales Forschungs- und Informationszentrum für öffentliche Wirtschaft, Sozialwirtschaft und Genossenschaftswesen = CIRIEC | Centre International de Recherches et d'Information sur l'Économie Publique, Sociale et Coopérative | In French |
In German | → Economics |
| IFIP | International Federation for Information Processing | In English | → Computer science |
| IFITT | International Federation of Information Technology and Tourism | In English | → Tourism |
| IFK | Internationales Forschungszentrum Kulturwissenschaften (www.ifk.ac.at) | In German | → Research institutes → Civilization, culture, progress |
| IFKF | International Federation of Kidney Foundations | In English | → Medicine |
| IFLA | International Federation of Library Associations | In English | → Libraries |
| IFLA | International Federation of Library Associations and Institutions | In English | → Associations → Libraries |
| IFM | Institut Français de la Mer | In French | → Research institutes → Environment, environmental sciences → Marine research, oceanography |
| IFOAM | International Federation of Organic Agriculture Movements | In English | → Agricultural sciences |
| IfP | Incontro fra i Popoli | In Italian | |
| IFP | Institut Français du Pétrole | In French | → Research institutes → Earth sciences → Mining → 665 |
| IFPCC | Institut Français des Praticiens des Procédures Collectives | In French | → Law, jurisprudence |
| IFPI | International Federation of the Phonographic Industry (www.ifpi.org) | In English | → Music |
| IFPMA | International Federation of Pharmaceutical Manufacturers & Associations (www.ifpma.org) | In English | → Pharmacology, toxicology |
| IFPS | International Federation of Palynological Societies | In English | → Paleobotany, palynology |
| IFR | Institute of Food Research | In English | → Research institutes → Agricultural sciences → Food technology |
| IFRA | INCA-FIEJ Research Association | In English | → Associations → Newspapers, journalism → Graphic industries, printing, publishing |
| IFRE | Internacia Forstista Rondo Esperantlingva | In Esperanto | → Agricultural sciences |
| IFRI | Institut Français des Relations Internationales | In French | → Research institutes → International relations |
| IFRTP | Institut Français pour la Recherche et la Technologie Polaire | In French | → Research institutes → Earth sciences |
| IFS | International Feuchtwanger Society | In English | |
| IFSH | Institut für Friedensforschung und Sicherheitspolitik | In German | → Research institutes → Polemology |
| IFT | Institute of Food Technologists | In English | → Research institutes → Food technology |
| IFT | International Federation of Translators (www.fit-ift.org) = FIT | Fédération Internationale des Traducteurs | In French |
In English | → Linguistics |
| IFTA | International Federation of Technical Analysts | In English | |
| IGDA | International Game Developers Association (www.igda.org) | In English | → Associations → Software → Entertainment |
| IGDD | Internationale Gesellschaft für Dialektologie des Deutschen | In German | → Language, linguistics, literature |
| IGEER | Instituut voor Geschiedenis van de Europese Expansie | In Dutch | → Research institutes → History |
| IGiPZ | Instytut Geografii i Przestrzennego Zagospodarowania (www.igipz.pan.pl) | In Polish | → Research institutes → Geography |
| IGN | Instituto Geográfico Nacional (www.ign.es) | In Spanish | → Research institutes → Geography |
| IGOR | Institut für Gewebe- und Organrekonstruktion (www.igor.at) | In German | → Research institutes → Biotechnology → Medicine |
| IGOST | Interdisziplinäre Gesellschaft für Orthopädische Schmerztherapie | In German | → Surgery, orthopaedics, ophthalmology |
| IGS | Ingénieurs-Géomètres Suisses = IGS | Ingenieur-Geometer Schweiz | In German |
In French | → Applied sciences, technology |
| IGS | Ingenieur-Geometer Schweiz = (look above) |
In German | → Applied sciences, technology |
| IGU | International Gas Union | In English | → Energy economics |
| IHF | Internationale Helsinki-Föderation für Menschenrechte (www.ihf-hr.org) = IHF | International Helsinki Federation for Human Rights | In English = IHF-HR | International Helsinki Federation for Human Rights | In English = МХФ | Международная хельсинская федерация по правам человека | In Russian |
In German | → Fundamental rights |
| IHF | International Helsinki Federation for Human Rights (www.ihf-hr.org) = IHF-HR, МХФ (look above) |
In English | → Fundamental rights |