| IHF-HR | International Helsinki Federation for Human Rights (www.ihf-hr.org) = IHF | International Helsinki Federation for Human Rights | In English = IHF | Internationale Helsinki-Föderation für Menschenrechte | In German = МХФ | Международная хельсинская федерация по правам человека | In Russian |
In English | → Fundamental rights |
| IHFCC | International Humanitarian Fact-Finding Commission (www.ihffc.org) = CIHEF | Commission Internationale Humanitaire d'Établisssement des Faits | In French |
In English | → International law |
| IHK | Industrie- und Handelskammer | In German | → Trade |
| IHP | Institute of History and Philology | In English | → Research institutes → Philology → History |
| IHR | Internacia Himalaja Renkontiĝo | In Esperanto | |
| IHSS | International Humic Substances Society | In English | → Earth sciences |
| IHTP | Institut d'Histoire du Temps Présent (www.ihtp.cnrs.fr) | In French | → Research institutes → History |
| IHV | Institute of Human Virology (www.ihv.org) | In English | → Research institutes → Virology |
| IHV | Internationaler Hunde Verein (www.ihv-online.de) | In German | |
| IHV | Innerschweizer Handballverband (www.ihv.ch) | In German | → Sport, physical exercises |
| IHV | Industrie- und Handelsvereinigung | In German | → Industry, industrial policy → Trade |
| II | Instytut Informatyk | In Polish | → Research institutes → Computer science |
| IIAC | Institut Interdisciplinaire d'Anthropologie du Contemporain | In French | → Research institutes → Sociology |
| IIAT | Institut International d'Agriculture Tropicale = IITA | International Institute of Tropical Agriculture | In English |
In French | → Research institutes → Agricultural sciences |
| IIBHG | Institute of Immunobiology and Human Genetics = IIBHG | Institut za Imunobiologija i Humana Genetika | In Macedonian |
In English | → Research institutes → Genetics → Immunology and allergy |
| IICD | International Institute for Communication and Development | In English | → Development |
| IICI | Institut International de Coopération Intellectuelle | In French | → International relations |
| IIDA | International Interior Design Association | In English | → Associations → Architecture → Drawing and applied arts |
| IIOC | Independent International Organisation for Certification | In English | → Standardization → Quality management |
| IIPA | International Iridology Practitioners Association | In English | → Associations → 6158 |
| IIPA | Israeli International Pharmacy Association | In English | → Associations → Pharmacology, toxicology |
| IIPA | International Industrial Photographers Association | In English | → Associations → Photography |
| IIPA | International Intellectual Property Alliance | In English | → Artistic property |
| IIPA | Irish Interprofessional Association | In English | → Associations |
| IISER | Indian Institute of Science and Education Research (www.iiserpune.ac.in) | In English | → Research institutes → Education |
| IITA | International Institute of Tropical Agriculture = IIAT (look above) |
In English | → Research institutes → Agricultural sciences |
| IJCAI | International Joint Conference on Artificial Intelligence | In English | → Congresses → Artificial intelligence |
| IJK | Internacia Junulara Kongreso | In Esperanto | → Congresses |
| IJM | Institut Jacques Monod (www.ijm.jussieu.fr) | In French | → Research institutes → Biological sciences |
| IJS | Internacia Junulara Semajno | In Esperanto | → Congresses |
| IJVC | IJlster Voetbal Club | In Dutch | → Football and rugby |
| IJVV | IJsselmuidener Voetbal Vereniging | In Dutch | → Football and rugby |
| IJVV | Ijmuidense Voetbal Vereniging | In Dutch | → Football and rugby |
| IKEF | Internacia Komerca kaj Ekonomia Fakgrupo | In Esperanto | → Trade |
| IKEK | Internacia Komunista Esperantista Kolektivo | In Esperanto | → Political parties and movements |
| IKEL | Internacia Komitato por Etnaj Liberecoj | In Esperanto | → Politics |
| IKEO | Internacia Kooperativa Esperanto-Organizo | In Esperanto | |
| IKKE | Interreta Konferenco de Komercemaj Esperantoparolantoj | In Esperanto | → Trade |
| IKSV | İstanbul Kültür Sanat Vakfı | In Turkish | → Foundations |
| IKUE | Internacia Katolika Unuigo Esperantista | In Esperanto | → Roman catholic church |
| ILAC | International Laboratory Accreditation Cooperation | In English | → Research institutes |
| ILAE | International Ligue Against Epilepsy (www.ilae.org) | In English | → Neurology |
| ILAR | Institute for Laboratory Animal Research (http://dels.nas.edu/ilar/) | In English | → Pharmacology, toxicology → Veterinary medicine |
| ILCA | (Research) Institute for Languages and Cultures of Asia and Africa | In English | → Research institutes → Civilization, culture, progress → Language, linguistics, literature → Area studies |
| ILEI | Internacia Ligo de Esperantistaj Instruistoj | In Esperanto | → Education |
| ILERA | Internacia Ligo de Esperantistaj Radioamatoroj | In Esperanto | → Telecommunications |
| ILM | Institut für Laboratoriumsmedizin, Klinische Chemie und Molekulare Diagnostik | In German | → Research institutes → Biochemistry, biophysics → Pharmacology, toxicology → 6160 |
| ILRF | International Labor Rights Fund | In English | → Labour, labour economics |
| ILS | International Libertarian Solidarity = SIL | Solidarité Internationale Libertaire | In French |
In English | → Political parties and movements |
| ILSSM | Israeli Society for Sexual Medicine | In English | → Sexual problems → Urology → Applied sciences, technology |
| ILSWG | Integrated Logistics Support Working Group | In English | → Maintenance and logistics |
| IM | Individua Membro | In Esperanto | |
| IMA | International Medical Association | In English | → Associations → Medicine |
| IMA | Interdisciplinary Medical Association | In English | → Associations → Medicine |
| IMADR | International Movement Against All Forms of Discrimination and Racism | In English | → Feminism |
| IMBA | Illinois Mortgage Bankers Association | In English | → Associations → Finance |
| IMBA | International Mountain Bicycling Association (www.imba.com) | In English | → Associations → Sport, physical exercises |
| IMBA | Internationale Motorsport Bond voor Amateurs (www.imba-mx.com) | In Dutch | → Vehicle engineering → Transport and postal services |
| IMCB | Institute of Molecular and Cell Biology | In English | → Research institutes → Biological sciences |
| IMCO | Intergovernmental Maritime Consultative Organization | In English | → International relations → 6295 → Transport and postal services |
| IMN | Instytut Metali Nieżelaznych (www.imn.gliwice.pl) | In Polish | → Research institutes → Metallurgy |
| IMP/LMM | Ingénierie des Matériaux Polymères/ Laboratoire Matériaux Macromoléculaires | In French | → Research institutes → 620 → Plastic industry |
| IMRSA | International Medical Regulatory and Shipping Association | In English | → Associations → Medicine |
| IMS | Institute for Molecular Science | In English | → Research institutes → Biochemistry, biophysics |
| IMS | National Museums of Scotland | In English | → Museums |
| IMSO | International Mobile Satellite Organization | In English | → Associations → Spaceflight engineering, astronautics → Telecommunications |
| INA | Istituto Nuova Africa | In Italian | |
| INA | Internacia Naturkuraca Asocio | In Esperanto | → Associations |
| INA | International Nanoplankton Association | In English | → Associations → Marine research, oceanography → Palaeontology → Zoology |
| INCA | International Newspaper Colour Association | In English | → Associations → Newspapers, journalism → Graphic industries, printing, publishing |
| INCOPA | Inorganic Coagulants Producers Association (www.incopa.org) | In English | → Associations → Chemicals |
| INED | Institut National d'Études Démographiques | In French | → Research institutes → Demography |
| INERIS | Institut National de l'Environnement Industriel et des Risques | In French | → Research institutes → Nature → Engineering, technology |
| INESASS | Institute of National Economy - Shanghai Academy of Social Sciences | In English | → Research institutes → Economics |
| İNETD | İnternet Teknolojileri Derneği | In Turkish | → Networks, communication |
| INETI | Instituto Nacional de Engenharia e Tecnologia Industrial | In Portuguese | → Research institutes → Engineering, technology |
| INGV | Istituto Nazionale di Geofisica e Vulcanologia (www.ingv.it) | In Italian | → Research institutes → Geophysics → 55121 |
| INJENO | INitiatives de parents de Jeunes Épileptiques du Nord | In French | → Neurology |
| INOE | Internacia Naturista Organizo Esperantista | In Esperanto | |
| INPMA | Institut National des Plantes Médicinales et Aromatiques | In English | → Research institutes → Biological sciences → Pharmacology, toxicology → Agricultural sciences |
| INRETS | Institut National de Recherche sur les Transports et leur Sécurité | In French | → Research institutes → Transport and postal services → Vehicle engineering |
| INRIA | Institut National de Recherche en Informatique et Automatique | In French | → Research institutes → Computer science → Electrical engineering |
| INRIA | Institut National de Recherche en Informatique et en Automatique | In French | → Research institutes → Computer science → Mechanical engineering |
| INRS | Institut National de Recherche et de Sécurité | In French | → Research institutes |
| INSP | Institut des Nanosciences de Paris | In French | → Research institutes → Physics → Chemistry |
| INSTM | Institut National des Sciences et des Techniques Nucléaires | In French | → Research institutes → Nuclear, atomic, and molecular physics → Nuclear technology |
| INTAP | Interoperability Technology Association for Information Processing | In English | → Associations → Telecommunications → Computer-based techniques |
| INTEC | International Netcourse Teacher Enhancement Coalition | In English | → Education |
| INTOSAI | International Organization of Supreme Audit Institutions | In English | → Accounting → 659 |
| IOAOB | Instituut voor de Organisatie van de Administraties der Openbare Besturen | In Dutch | → Research institutes → Libraries |
| IOB | Institute of Biology | In English | → Research institutes → Biological sciences |
| IOC | International Olympic Committee (www.olympic.org) = CIO | Comité International Olympique | In French = МОК | Международен олимпийски комитет | In Bulgarian = MOO | Međunarodni olimpijski odbor | In Bosnian = COI | Comitè Olímpic Internacional | In Catalan = MOV | Mezinárodní olympijský výbor | In Czech = IOK | Internationales Olympisches Komitee | In German = ΔΟΕ | Διεθνής Ολυμπιακή Επιτροπή | In Greek = IOK | Internacia Olimpika Komitato | In Esperanto = COI | Comité Olímpico Internacional | In Spanish = ROK | Rahvusvaheline Olümpiakomitee | In Estonian = KOK | Kansainvälinen olympiakomitea | In Finnish = COI | Comité Olímpico Internacional | In Galician = MOO | Međunarodni olimpijski odbor | In Croatian = NOB | Nemzetközi Olimpiai Bizottság | In Hungarian = TOK | Tarptautinis olimpinis komitetas | In Lithuanian = IOC | Internationaal Olympisch Comité | In Dutch = IOK | (Den) internasjonale olympiske komité | In Norwegian = MKOI | Międzynarodowy Komitet Olimpijski | In Polish = COI | Comité Olímpico Internacional | In Portuguese = МОК | Международный олимпийский комитет | In Russian = MOK | Međunarodni olimpijski komitet | In Serbo-Croatian = MOV | Medzinárodný olympijský výbor | In Slovak = MOK | Mednarodni olimpijski komite | In Slovenian = МОК | Међународни олимпијски комитет | In Serbian = IOK | Internationella Olympiska Kommitté | In Swedish = МОК | Міжнародний олімпійський комітет | In Ukrainian |
In English | → Sport, physical exercises |
| IOC | Internationaal Olympisch Comité (www.olympic.org) = CIO, МОК, MOO, COI, MOV, IOK, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Dutch | → Sport, physical exercises |
| IOK | Internationales Olympisches Komitee (www.olympic.org) = IOC, CIO, МОК, MOO, COI, MOV, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In German | → Sport, physical exercises |
| IOK | (Den) internasjonale olympiske komité (www.olympic.org) = IOC, CIO, МОК, MOO, COI, MOV, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Norwegian | → Sport, physical exercises |
| IOK | Internacia Olimpika Komitato (www.olympic.org) = IOC, CIO, МОК, MOO, COI, MOV, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Esperanto | → Sport, physical exercises |
| IOK | Internationella Olympiska Kommitté (www.olympic.org) = IOC, CIO, МОК, MOO, COI, MOV, ΔΟΕ, ROK, KOK, NOB, TOK, MKOI, MOK (look above) |
In Swedish | → Sport, physical exercises |
| IOLM | International Organization of Legal Metrology | In English | → Standardization |
| IOM | International Organization for Migration | In English | → Migrations |
| IOM | Interoceanmetal Joint Organization | In English | → Marine research, oceanography → Mining |
| IOP | International Organisation of Palaeobotany | In English | → Paleobotany, palynology |
| IOPAN | Instytut Oceanologii Polskiej Akademii Nauk (www.iopan.gda.pl) | In Polish | → Research institutes → Marine research, oceanography |
| IOSCS | International Organization for Septuagint and Cognate Studies | In English | → Judaism → Christianity |
| IOT | Inspraakorgaan Turken (in Nederland) | In Dutch | → Migrations |
| IPA | Internet Privatstiftung Austria | In German | → Foundations → Networks, communication → Telecommunications |
| IPA | International Powerlifting Association | In English | → Associations |
| IPA | Interparlamentarische Arbeitsgemeinschaft | In German | → Associations → Parliaments, representation |
| IPA | International Phonetic Association | In English | → Associations → Writing systems |
| IPA | Independent Pilots Association | In English | → Associations → Aeronautics, aircraft |
| IPA | Independent Practice Association | In English | → Associations → Medicine |
| IPA | International Psychoanalytical Association | In English | → Associations → Psychology |
| IPA | International Police Association | In English | → Associations → Police |
| IPA | International Publishers' Association | In English | → Associations → Graphic industries, printing, publishing |
| IPA | Fraunhofer-Institut für Produktionstechnik und Automatisierung | In German | → Research institutes → Engineering, technology |
| IPB | International Peace Bureau | In English | → Polemology |
| IPC | Institut de Pathologie du Cheval | In French | → Research institutes → Veterinary medicine → Agricultural sciences |
| IPCAA | International Pharmaceutical Congress Advisory Association | In English | → Associations → Congresses → Pharmacology, toxicology |
| IPEA | Internet Positionning European Association | In English | → Associations → Networks, communication → 659 |
| IPF | Internet pour la France | In French | → Internet → Telecommunications |
| IPFA | International Plasma Fractionation Association | In English | → Associations → Pharmacology, toxicology |
| IPIG | ILL Protocol Implementers Group | In English | → Networks, communication → Libraries |
| IPK | Institut für Produktionsanlagen und Konstruktionstechnik (www.ipk.fraunhofer.de) | In German | → Research institutes → Building |
| IPN | Instytut Pamięci Narodowej - Komisja Ścigania Zbrodni przeciwko Narodowi Polskiemu (www.ipn.gov.pl) | In Polish | → Research institutes → Law, jurisprudence → History |
| IPN | Institut für Biophysik und Nanosystemforschung | In German | → Research institutes → Biochemistry, biophysics |
| IPO | International Progress Organization (www.i-p-o.org) | In English | → International relations |
| IPPA | Indo-Pacific Prehistory Association | In English | → Associations → Prehistory |
| IPPS | The International Plant Propagators Society | In English | → Agricultural sciences |
| IPPS | International Parallel Processing Symposium | In English | → Congresses → Computer-based techniques → Mathematics |
| IPPS | International Pre-Platonic Studies | In English | → Philosophy, psychology → Literature |
| IPPS | International Pelvic Pain Society | In English | → Pathology |
| IPPS | International Plant Propagators Society | In English | → Agricultural sciences |
| IPPT | Instytut Podstawowych Problemów Techniki (www.ippt.gov.pl) | In Polish | → Research institutes → Engineering, technology |
| IPRC | International Pacific Research Center | In English | → Research institutes → International relations → Area studies |
| IPRCS | Irish Pattern Recognition and Classification Society | In English | → Computer-based techniques |
| IPS | International Primatological Society (www.internationalprimatologicalsociety.o) | In English | → Zoology |
| IPSJ | Information Processing Society of Japan | In English | → Computer-based techniques |
| IPTEA | Internacia Poŝtista kaj Telekomunikista Esperanto-Asocio | In Esperanto | → Associations → Telecommunications → Transport and postal services |
| IQSA | International Qajar Studies Association | In English | → Associations |
| IRAM | Institut de Radioastronomie Millimétrique | In French | → Research institutes → Astronomy |
| IRAS | Istituto Spezzino Ricerche Astronomiche | In Italian | → Research institutes → Astronomy |
| IRAS | Interreligiöse Arbeitsgemeinschaft in der Schweiz | In German | → Associations → Religion, theology |
| IRB | International Rugby Board | In English | → Football and rugby |
| IRCAM | Institut de Recherche et Coordination Acoustique/Musique (www.ircam.fr) | In French | → Research institutes → Music |
| IRCCS | Istituto di Ricovero e Cura a Carattere Scientifico | In Italian | → Research institutes → Research policy |
| IRCCyN | Institut de Recherche en Communications et Cybernétique de Nantes (www.irccyn.ec-nantes.fr) | In French | → Research institutes → Telecommunications → Electronics |
| IRCICA | Research Centre for Islamic History, Art and Culture | In English | → Research institutes → Islam → Arts → History → Civilization, culture, progress |
| IrDA | Infrared Data Association | In English | → Associations → Telecommunications |
| IRE | Institutul Naţional Român pentru Studiul Amenajării şi Folosirii Surselor de Energie | In Romanian | → Energy economics |
| IREA | Irana Esperanto-Asocio | In Esperanto | → Associations |
| IREJO | Irana Esperantista Junulara Organizo | In Esperanto | |
| IREM | Institut de Recherches sur l'Enseignement des Mathématiques | In French | → Research institutes → Education → Mathematics |
| IRES | Institut de Recherches Économiques et Sociales | In French | → Research institutes → Social sciences → Economics |
| IRESCO | Institut de Recherche sur les Sociétés Contemporaines | In French | → Research institutes → Sociology |
| IRESCO | Institut de Recherche Européen en Sociologie et Socio-économie | In French | → Research institutes → Sociology → Economics |
| IRI | Institut de Recherche et d'Innovation (www.iri.centrepompidou.fr) | In French | → Research institutes → Research policy → Civilization, culture, progress |
| IRIS | Incorporated Research Institutions for Seismology (www.iris.edu) | In English | → Research institutes → Seismology, earthquakes |
| IRIS | Inter-Regiona Internacia Semajno | In Esperanto | → Congresses |
| IRIS | Imaginons un Réseau Internet Solidaire | In French | → Internet |
| IRIS | Institut des Relations Internationales et Stratégiques (www.iris-france.org) | In English | → Research institutes → International relations |
| IRIT | Institut de Recherche en Informatique de Toulouse | In French | → Research institutes → Computer science |
| IRIT | Institut de Recherche Informatique de Toulouse (www.irit.fr) | In French | → Research institutes → Computer science |
| IRIZ | International Research Institute for Zen Buddhism (http://iriz.hanazono.ac.jp) | In English | → Research institutes → Buddhism |
| IRPI | Institut de Recherche en Propriété Intellectuelle (www.irpi.ccip.fr) | In French | → Research institutes → Artistic property |
| IRRI | International Rice Research Institute (www.irri.org) | In English | → Research institutes → Agricultural sciences |
| IRSC | Instituts de recherche en santé du Canada (www.cihr.ca) = CIHR | Canadian Institutes of Health Research | In English |
In French | → Research institutes → Biological sciences → Medicine |
| IRSEA | Institut de Recherche sur le Sud-Est Asiatique (www.univ-provence.fr/irsea/) | In English | → Research institutes → Area studies |
| IRSN | Institut de Radioprotection et de Sécurité Nucléaire | In French | → Research institutes → Nuclear technology |
| IRT | Institut für Rundfunktechnik (www.irt.de) | In German | → Research institutes → Telecommunications |
| IRTC | International Rehabilitation Council for Torture | In English | → Fundamental rights |
| IS | Internacia Seminario | In Esperanto | → Congresses |
| ISA | International Seabed Authority (www.isa.org.jm) | In English | → International relations → Marine research, oceanography → Mining |
| ISA | International Sociological Association | In English | → Associations → Sociology |
| ISAE | Internacia Scienca Asocio Esperantista | In Esperanto | → Associations → Mathematics and natural sciences |
| ISAFIS | Indonesian Student Association for International Studies | In English | → Associations → Higher education, universities |
| ISAZ | International Society for Anthrozoology | In English | → Zoology |
| ISBL | Institution(s) sans but lucratif | In French | |
| ISBS | Internationales Symposium für Biomechanik im Sport | In German | → Congresses → Biological sciences → Sport, physical exercises |
| ISC | International Seismological Centre (www.isc.ac.uk) | In English | → Research institutes → Seismology, earthquakes |
| ISC | Ingense Sport Club | In Dutch | → Sport, physical exercises |
| ISCAR | International Society for Cultural and Activity Research | In English | → Social sciences → Civilization, culture, progress |
| ISCOS | Istituto Sindacale per la Cooperazione allo Sviluppo | In Italian | → Development |
| ISD | International Society of Differentiation | In English | → Biological sciences |
| ISDP | International Society for Developmental Psychobiology (www.isdp.org) | In English | → Developmental psychology → Biological sciences |
| ISDP | International Society of Dermatopathology | In English | → Dermatology |
| ISDP | Institute for Security & Development Policy (www.isdp.eu) | In English | → Research institutes → Politics → Development |
| ISE | Internacia Semajnfino Esperantista | In Esperanto | → Congresses |
| ISE | Institut Syndical Européen | In French | → Labour, labour economics |
| ISEGI | Instituto Superior de Estatística e Gestão de Informação | In Portuguese | → Research institutes → Statistics |
| ISEM | Institut des Sciences de l'Évolution de Montpellier | In French | → Research institutes → Biological sciences |
| ISER | Institute for Social and Economic Research | In English | → Research institutes → Demography, statistics, sociology → Economics |
| ISF | Ingénieurs Sans Frontières | In French | → Engineering, technology |
| ISFP | International Society for Fibrinolysis and Proteolysis | In English | → Biochemistry, biophysics |
| ISHEASTM | International Society for the History of East Asian Science Technology and Medicine | In English | → History → Medicine → Engineering, technology |
| ISHS | International Society for Horticultural Science | In English | → Horticulture |
| ISI | Integral Satcom Initiative (www.isi-initiative.eu.org) | In English | → 645 → Spaceflight engineering, astronautics |
| ISIAO | Istituto italiano per l'Africa e l'Oriente | In Italian | |
| ISIR | International Society for Interferon-Research | In English | → Biochemistry, biophysics → Medicine |
| ISIR | Institut des Systèmes Intelligents et de Robotique | In French | → Research institutes → Artificial intelligence → Electrical engineering → Engineering, technology |
| ISIR | Institut des Systèmes Intelligents et Robotique | In French | → Research institutes → Mechanical engineering → Electronics |
| ISIR | Institut für Statistik und internationale Registrierungen | In German | → Research institutes → Statistics |