LibGuides: GovSpeak: A Guide to U.S. Government Acronyms & Abbreviations: I

I2U2	India, Israel, United Arab Emirates, United States
i2X	Interconnection Innovation e-Xchange (older link archive)
i3	Investing In Innovation
I&A	Industry & Analysis (older link archive; archive2) \| Office of Intelligence and Analysis
I&M	Biological Inventory and Monitoring (changed to ECO) \| Inventory and Monitoring (older link archive)
I&O	Industry and Occupation (older link archive)
IA	International Affairs (changed to International Operations; older link archive) \| Import Administration (changed to Enforcement and Compliance; older link archive) \| Indian Affairs \| Office of International Affairs (older link archive)
IAAF	Interagency Accessibility Forum (older link archive)
IAAO	International and Academic Affairs Office
IAB	InterAgency Board
IABC	International Analysis and Banking Condition Division (unable to verify 10/19)
IAC	Industrial Advisory Committee \| Industrial Assessment Center (older link archive) \| Inventors Assistance Center \| White House Environmental Justice Interagency Council
IACB	Indian Arts and Crafts Board
IACC	Interagency Autism Coordinating Committee
IACT	Institute for Atom-Efficient Chemical Transformations (unable to verify 6/19; older link archive)
IAD	Industry Analysis Division \| Information Access Division \| Information Assurance Directorate (changed to Cybersecurity; older link archive) \| International Affairs Division, ATF \| International Affairs Division, TTB (older link archive; archive2; archive3) \| Investigative Analysis Division (older link archive)
IADRP	International Alzheimer's and Related Dementias Research Portfolio (older link archive)
IADRWG	Interagency Alternative Dispute Resolution Working Group

IAE	Integrated Award Environment (older link archive; archive2; archive3)
IAEGC	Inter-Agency Electronic Grants Committee (changed to grants.gov)
IAEM	Institute for Advanced Electron Microscopy
IAF	Inter-American Foundation
IAG	Indigenous Animals Harvesting and Meat Processing Grant Program \| Industries at a Glance
IAIP	Infrastructure Analysis and Infrastructure Protection Program (unable to verify 1/08)
IAIWG	International Activities Interagency Working Group (older link archive)
IAL	Innovative Approaches to Literacy (older link archive)
IALS	International Adult Literacy Survey
IAM	Indian Affairs Manual (older link archive)
IAO	Interagency Office (unable to verify 7/22)
IAP	International Activities Program \| International Agricultural Productivity \| Medicaid Innovation Accelerator Program (older link archive; archive2)
IAPD	Investment Adviser Public Disclosure (older link archive)
IAPE	Office of Intergovernmental Affairs and Public Engagement
IAQ	Indoor Air Quality
IARPA	Intelligence Advanced Research Projects Activity
IARPC	Interagency Arctic Research Policy Committee
IASA	International Aviation Safety Assessment
IASAP	Indian Alcohol and Substance Abuse Program (unable to verify 12/18)
IASOA	International Arctic Systems for Observing the Atmosphere (unable to verify 4/23; older link archive)
IASP	Integrated Aviation Systems Program (older link archive)
IAT	Interagency Aviation Training
IATP	Intelligence Analyst Training Program (unable to verify 8/18)
IAWG	Interagency Working Group
IB	Intelligence Branch (older link archive) \| International Bureau (changed to OIA)
IBA	Industrial Base Assessments (changed to IPA)
IBAS	Industrial Base Analysis and Sustainment (unable to verify 5/23)
IBAT	Interagency Bolt Action Team

IBB	International Broadcasting Bureau (changed to BBG)
IBC	Interior Business Center
IBCE	Institute of Bioenergy, Climate, and Environment (older link archive)
IBEX	Interstellar Boundary Explorer (older link archive)
IBFS	International Bureau Electronic Filing System (older link archive)
IBIA	Interior Board of Indian Appeals
IBIP	Indian Business Incubators Program
IBIS	International Biometric Information Sharing Program (older link archive)
IBLA	Interior Board of Land Appeals (older link archive)
IBMP	Interagency Bison Management Plan
IBN	Indicators of Broadband Need
IBP	Industrial Base Policy \| International Buyer Program (unable to verify 4/23)
IBR	Incorporation by Reference \| Industrial Base Resilience
IBRC	Innovative Bridge Research and Construction Program (unable to verify 1/15)
IBRD	Innovative Bridge Research and Deployment Program (unable to verify 1/15)
IBS	International Banking Supervision
IBTrACS	International Best Track Archive for Climate Stewardship (older link archive)
IBWC	International Boundary and Water Commission (older link archive)
IBx	Program Office for Innovation and Industrial Base Expansion (older link archive)

IC	Intelligence Community
IC ACC	Intelligence Community Advanced Campaign Cell
IC3	Internet Crime Complaint Center (older link archive)
ICAC	Internet Crimes Against Children Task Force Program (unable to verify 10/19)
ICAD	Intelligent Computer Assisted Detection
ICAM	Identity, Credential, and Access Management \| Innovative Coordinated Access and Mobility Pilot Program
ICAMS	Interagency Council for Advancing Meteorological Services
ICARS	Interagency Council on Agricultural and Rural Statistics
ICASS	International Cooperative Administrative Support Services (older link archive; archive2)
ICATT	Increasing Community Access to Testing for COVID-19
ICBEMP	Interior Columbia Basin Ecosystem Management Project (archived site; older link archive; archive2)
ICBS-R	Interagency Cache Business System Re-engineering
ICC	Census Integrated Communications Campaign \| Office of Incident Command and Control (older link archive)
ICCA	International Conservation Chiefs Academy (older link archive)
ICCE	Office of International Climate and Clean Energy (discontinued)
ICCPUD	Interagency Coordinating Committee on the Prevention of Underage Drinking (alternate link archive)
ICCVAM	Interagency Coordinating Committee on the Validation of Alternative Methods (older link archive; archive2)
ICD	Intelligence Community Directive \| Interagency Contract Directory \| International Classification of Diseases (older link archive; archive2)
ICDBG	Indian Community Development Block Grant (older link archive)
ICDR	Interagency Committee on Disability Research (older link archive)
ICE	Immigration and Customs Enforcement \| Infrastructure Carbon Estimator
ICEIWG	Indian Country Energy and Infrastructure Working Group (older link archive)
ICESat-2	Ice, Cloud, and Land Elevation Satellite-2
ICF	International Classification of Functioning, Disability and Health \| Office of Inertial Confinement Fusion (unable to verify 8/18)
ICH	Interagency Council on Homelessness
ICHNR	Interagency Committee on Human Nutrition Research
ICILS	International Computer and Information Literacy Study

ICIS	Integrated Compliance Information System
ICITAP	International Criminal Investigative Training Assistance Program (older link archive)
ICLUS	Integrated Climate and Land-Use Scenarios (older link archive; archive2; archive3)
ICM	Integrated Corridor Management
ICMOB	Intramural Clinical Management and Operations Branch
ICOADS	International Comprehensive Ocean-Atmosphere Data Set
ICON	Ionospheric Connection Explorer (older link archive)
ICOR	Immigration Court Online Resource
I-Corps	Innovation Corps
iCOUP	Institute for the Cooperative Upcycling of Plastics
ICP	Indian Children's Program (older link archive) \| Informed Compliance Publication \| International Information and Communications Policy
ICPD	Individual and Community Preparedness Division (older link archive; archive2)
ICPG	Intelligence Community Policy Guidance
ICPM	Intelligence Community Policy Memorandum
ICPO	International Cooperative Programs Office
ICPPS	Interagency Council on Printing and Publications Services (replaced by FPC; older link archive)
ICR	Information Collection Request \| Information Collection Review \| Information Collection Rule \| Information Coordination and Reporting Branch (older link archive)
ICRO	Information Collection Review Office
ICS	Incident Command System (older link archive; archive2) \| Industrial Control Systems (older link archive) \| International Cyberspace Security \| Investment Climate Statements
ICS-CERT	Industrial Control Systems Cyber Emergency Response Team (retired 2/23; previously merged into NCCIC)
ICSJWG	Industrial Control Systems Joint Working Group

ICSO	Interior Complex Security Operations
ICSP	Interagency Committee on Standards Policy (older link archive; archive2) \| Interagency Council on Statistical Policy
ICT	Indigenous Connectivity and Technology Division
ICTAP	Interoperable Communications Technical Assistance Program (older link archive)
ICTIME	Interagency Center for Trade Implementation, Monitoring, and Enforcement
ICTS	Information and Communication Technology Survey
ICU	Influenza Coordination Unit (unable to verify 2/16)
ID	Infectious Diseases (older link archive; archive2) \| Influenza Division (older link archive) \| Intelligence Division (older link archive; archive2)
IDA	Individual Development Accounts (older link archive) \| Interactive Data Analyzer
IDB	International Data Base (older link archive) \| Investigational Drug Branch
IDC	Imaging Data Commons
ID-CTP	Immune Deficiency Cellular Therapy Program
IDD	Infrastructure Protection and Disaster Management Division (unable to verify 5/14)
IDDB	Intellectual and Developmental Disabilities Branch
IDE	International Data Explorer
IDEA	Index of Economic Activity \| Individuals with Disabilities Education Act
IDEAS	IARPA Distribution & Evaluation System \| Interagency Disability Educational Awareness Showcase (unable to verify 8/13) \| Inter-Disciplinary Engagement in Animal Systems (older link archive; archive2)
IDENT	Automated Biometric Identification System
IDEP	Integrated Diabetes Education Program (defunct)
IdHSC	Identity History Summary Checks (older link archive; archive2)
IDIS	Integrated Disbursement and Information System
IDLH	Immediately Dangerous To Life or Health
IDMS	Investigations Data Management System
IDN	International Directory Network
IDPB	Infectious Diseases Pathology Branch (older link archive)
IDR	Income-Driven Repayment
IDS	Incident Data System \| Investigations Database System
IDSR	Integrated Disease Surveillance and Response (older link archive)

IEA	Integrated Ecosystem Assessments \| Office of Independent Enterprise Assessments (changed to EA) \| Office of Intergovernmental and External Affairs (older link archive)
IEC	International Energy Commitments
IECMH	Infant Early Childhood Mental Health
IECMHC	Center of Excellence for Infant and Early Childhood Mental Health Consultation (older link archive)
IED	Office of Indian Economic Development
iEdison	Interagency Edison (older link archive)
IEDO	Industrial Efficiency and Decarbonization Office (older link archive)
IEED	Office of Indian Energy and Economic Development (changed to IED; older link archive)
IEG	Instrument Enhanced Grading program
IEIP	International Emerging Infections Program (unable to verify 9/23)
IELS	International Early Learning Study
IENC	Inland Electronic Navigational Charts
IEO	International Energy Outlook
IER	Immigrant and Employee Rights Section
IERH	International Emergency and Refugee Health (changed to ERRB)
IES	Institute of Education Sciences \| International Energy Statistics \| Investigative and Enforcement Services (older link archive)
IESC	Indian Energy Service Center (older link archive; archive2)
IEUBK	Integrated Exposure Uptake Biokinetic
IE&VT	Industries, Education, and Vocational Training Division (unable to verify 8/17)
IFAC	In-Field Address Canvassing
IFAP	Information for Financial Aid Professionals (changed to Knowledge Center then FSA Partner Connect)
I-FAST	Innovations in Food and Agricultural Science and Technology Prize Competition (unable to verify 3/21)
IFD	Division for International Finance and Development
IFDP	International Finance Discussion Papers (older link archive)
iFECS	integrated Federal Employees' Compensation System
IFFC	Illicit Finance Fusion Cell
IFLE	International and Foreign Language Education
IFMAT	Indian Forest Management Assessment Team
IFO	International Field Offices
IFPM	Interagency Fire Program Management Standard
IFPS	Institute of Food Production and Sustainability (older link archive; archive2; archive3; archive4)
IFS	Center for Innovative Finance Support
IFSAC	Interagency Food Safety Analytics Collaboration (older link archive)

IFSN	Institute of Food Safety and Nutrition (older link archive; archive2; archive3; archive4; archive5)
IFTDSS	Interagency Fuel Treatment Decision Support System
IFU	International Field Units (unable to verify 4/15)
IGA	Office of Intergovernmental Affairs (older link archive; archive2)
IGBST	Interagency Grizzly Bear Study Team
IGCE	Independent Government Cost Estimate
IGEMS	Interior Geospatial Emergency Management System (unable to verify 2/18)
IGIA	Interagency Group on Insular Areas (older link archive; archive2)
IGIM	Interagency Group on Integrative Modeling (older link archive)
IGMS	Integrated Grants Management System (changed to NGGS; older link archive)
IGNITE	Implementing Genomics in Practice \| Inspector General Network for Information and Telecommunications Exchange
IGP	Office of Information Governance and Privacy (changed to OIGP; older link archive)
IGRA	Integrated Global Radiosonde Archive (older link archive)
IGSB	Institute for Genomics & Systems Biology (unable to verify 4/19)
IHA	Indian Housing Authority (changed to PIH)
IHB	Office of International Health and Biodefense (unable to verify 9/23)
IHBG	Indian Housing Block Grant (older link archive)
IHCIF	Indian Health Care Improvement Fund
IHEC	Interdepartmental Health Equity Collaborative (older link archive)
IHM	Images from the History of Medicine (older link archive) \| Indian Health Manual
IHP	Individuals and Households Program
IHPES	Indian Health Performance Evaluation System
IHR	International Health Regulations
IHRU	International Human Rights Unit
IHS	Indian Health Service
IHSC	Immigration and Customs Enforcement Health Service Corps (older link archive)
IHSDM	Interactive Highway Safety Design Model

IIA	Office of International and Integrative Activities (changed to OIA)
IIAD	International and Interagency Affairs Division (older link archive)
IIB	Infections and Immunoepidemiology Branch (older link archive)
IIC	Institute for Integrated Catalysis
IID	Inactive Ingredient Database (older link archive)
IIF	Injuries, Illnesses, and Fatalities
III	Interstate Identification Index (older link archive; archive2)
IIM	Individual Indian Money Accounts
IIMD	Identity and Information Management Division (older link archive)
IIOG	Interagency Interoperability Oversight Group (unable to verify)
IIP	Bureau of International Information Programs (unable to verify 6/19; older link archive) \| Division of Industrial Innovation and Partnerships (replaced by TIP) \| Innovation and Intellectual Property
IIRD IWG	Information Integrity R&D Interagency Working Group
IIS	Division of Information & Intelligent Systems (older link archive) \| Immunization Information Systems (older link archive)
IISAR	Immunization Information Systems Annual Report (older link archive)
IITF	International Institute of Tropical Forestry (older link archive)

IJC	International Joint Commission
ILA	Independent Living Administration (unable to verify 4/20; older link archive)
ILAB	Bureau of International Labor Affairs
ILC	International Labor Comparisons
ILCP	Indian Land Consolidation Program (older link archive)
ILD	Intelligence Law Division
ILER	Individual Longitudinal Exposure Record
ILGP	Indian Loan Guarantee and Insurance Program
ILINet	U.S. Outpatient Influenza-like Illness Surveillance Network
ILN	Intelligence Learning Network (older link archive; archive2)
IL-OIB	Independent Living Services for Older Individuals Who Are Blind
ILS	Independent Living Services
iLSA	Institute for Laser Science Applications (changed to CHEDS)
IM	Division of Investment Management (older link archive; archive2)
IMAAC	Interagency Modeling and Atmospheric Assessment Center
IMACS	International Myositis Assessment and Clinical Studies Group
IMAGE	ICE Mutual Agreement between Government and Employers (older link archive)
IMAP	Interstellar Mapping and Acceleration Probe
IMAT	Innovative Molecular Analysis Technologies
IMATS	Inventory Management and Tracking System (unable to verify 1/20)

IMC	Imaging Mass Cytometry Laboratory \| Interagency Management Council for Federal Telecommunications (unable to verify 12/12)
IMCO	Interagency Meteorological Coordination Office
IMCP	Investing in Manufacturing Communities Partnership (unable to verify 4/20)
IMDCC	Interagency Marine Debris Coordinating Committee (older link archive; archive2)
IMDS	International Macroeconomic Data Set
IME	Institute of Molecular Engineering (unable to verify 9/17)
IMF	International Monetary Fund
IMG/M	Integrated Microbial Genomes & Microbiomes
IMG/VR	Integrated Microbial Genomes/Virus
IMIS	Integrated Management Information System
IML	Irradiated Materials Laboratory
IMLGS	Index to Marine and Lacustrine Geological Samples
IMLS	Institute of Museum and Library Services
IMM	Immigration Law Division
IMMDL	Insect Management and Molecular Diagnostics Laboratory (older link archive)
IMMPaCt	International Micronutrient Malnutrition Prevention and Control Program (older link archive; archive2)
ImmPort	Immunology Database and Analysis Portal
IMP	Inventory Management Plan
IMPACT	Interagency Implementation and Advanced Concepts Team
IMPACT-MH	Individually Measured Phenotypes to Advance Computational Translation in Mental Health
IMS	Interactive Multisensor Snow and Ice Mapping System
IMS/PIC	Inventory Management System/PIH Information Center
INA	Office of International Affairs
INADs	Investigational New Animal Drugs
INB	Integrative Neuroscience Branch (older link archive; archive2)
InCA	Interactive Cancer Atlas (unable to verify 8/18; likely changed to USCS Data Visualizations)
INCA	Interagency National Climate Assessment Working Group (unable to verify 2/18)
InciWeb	Incident Information System (older link archive)
INCSR	International Narcotics Control Strategy Report (older link archive; archive2)
INCUS	Investigation of Convective Updrafts

IND	Interplanetary Network Directorate (older link archive) \| Investigational New Drug (older link archive)
IndIWG	Indicators Interagency Working Group (older link archive)
INEAP	Interagency Network of Enterprise Assistance Providers (unable to verify 9/16)
INEPC	Office of International Nuclear Energy Policy and Cooperation
INF	Intermediate Range Nuclear Forces (older link archive; archive2; archive3; archive4)
InfoLaw	Information Law Division
INFRA	Infrastructure for Rebuilding America (older link archive; archive2; archive3)
InFRM	Interagency Flood Risk Management
INL	Bureau for International Narcotics and Law Enforcement Affairs (older link archive) \| Idaho National Laboratory
INL/AME	Office of Africa and Middle East Programs (unable to verify 6/19)
InPort	NMFS Information Portal (older link archive)
INR	Bureau of Intelligence and Research (older link archive; archive2)
INRMPs	Integrated Natural Resources Management Plans
INS	Immigration and Naturalization Service (changed to USCIS)
INSD	FBI Inspection Division
INSITE	INtegrated Support for Impacted air-Traffic Environments (unable to verify 11/23; older link archive)
INSTINCT	Infrastructure for Noise and Soundscape Tolerant Investigation of Nonspecific Call Types
INT	Office of International Affairs (DOI)
INTEGRAL	International Gamma-ray Astrophysics Laboratory
INTERPOL	International Criminal Police Organization
INVNT	CBP Innovation Team
IO	Bureau of International Organization Affairs (older link archive)
IOC/AG	Information Operations Center’s Analysis Group (unable to verify 2/17)
IOCM	Integrated Ocean and Coastal Mapping
IOD	Indexing on Demand \| International Operations Division (older link archive)
IOLP	Inventory of Owned and Leased Properties (older link archive; archive2; archive3; archive4)
IOMs	Internet Only Manuals (older link archive; archive2)
IOOC	Interagency Ocean Observation Committee
IOOS	Integrated Ocean Observing System
IOS	Division of Integrative Organismal Systems
IOSS	Interagency OPSEC Support Staff (decommissioned 12/22) \| Investigative and Operations Support Section (unable to verify 8/22)

IP	Intellectual Property Section \| Office of Infrastructure Protection (changed to ISD)
IPA	Industrial Policy and Analysis (older link archive)
IPaC	Information for Planning and Consultation (changed from Information, Planning, and Conservation; older link archive)
IPAD	International and Philanthropic Affairs Division \| International Production Assessment Division (older link archive)
IPAS	Illicit Pathways Attack Strategy (older link archive)
IPAWS	Integrated Public Alert & Warning System
IPB	Inspection Policy Branch
IPC	Integrated Partnership and Communication
IPCA	International Parental Child Abduction
IPCD	Intermodal Passenger Connectivity Database (older link archive; archive2)
IPD	Innovative Program Delivery (changed to CIFS) \| International Programs Division (unable to verify 11/22)
IPDD	Institutional Programs Development Division
IPE	Immunization Program Evaluation
IPEC	Intellectual Property Enforcement Coordinator (older link archive)
IPEDS	Integrated Postsecondary Education Data System
IPEF	Indo-Pacific Economic Framework for Prosperity
IPEMF	Integrated Physical and Ecological Modeling and Forecasting
IPEP	Intellectual Property Theft Enforcement Program (older link archive; archive2)
IPG	Industry Proving Grounds
IPHIS	Integrated Plant Health Information System
IPI	Bureau for Inclusive Growth, Partnerships, and Innovation \| International and Philanthropic Innovation (changed to IPAD)
IPIF	Institute of Pacific Islands Forestry (older link archive; archive2)
IPL	Intergovernmental Public Liaison
IPM	Integrated Pest Management, FWS (unable to verify 2/16) \| Integrated Pest Management, NIFA (older link archive)
IPP	Import Permit Program (older link archive; archive2) \| Innovative Partnerships Program (changed to ITPO) \| Unmanned Aircraft System Integration Pilot Program \| Invoice Processing Platform
IPR	Interatomic Potentials Repository
IPR Center	National Intellectual Property Rights Coordination Center
IPRiS	Intellectual Property Rights Internal Search System
IPRL	Invasive Plant Research Laboratory (older link archive)
IPRP	Interagency Pain Research Portfolio (older link archive; archive2)
IPRR	Intellectual Property Rights e-Recordation Online System
IPRS	Intellectual Property Rights Search
IPS	Images and Publications System, NCDC
IPTF	Intellectual Property Task Force (unable to verify / website archived 1/22)
IPTU	International Prisoner Transfer Program (older link archive; archive2)
IPY	International Polar Year
IQCP	Individualized Quality Control Plan
IQIP	Immunization Quality Improvement for Providers (older link archive)

IRA	Industry and Regional Analysis Division (unable to verify 10/19)
IRAC	Interdepartment Radio Advisory Committee
IRAD	International and Refugee Affairs Division
IRAP	International Research and Applications Project (unable to verify 9/23; older link archive; archive2; archive3)
IRAS IWG	Intelligent Robotics and Autonomous Systems Interagency Working Group
IRAT	Influenza Risk Assessment Tool (older link archive) \| Inorganic and Radiation Analytical Toxicology Branch (older link archive)
IRB	Internal Revenue Bulletin (older link archive)
IRDA	Informatics Research and Development Activity (unable to verify 6/14; likely replaced by DHIS)
IREMS	Integrated Real Estate Management System
IRENE	Image, Reconstruct, Erase Noise, Etc.
IREPO	Institutional Resilience and Expanded Postsecondary Opportunity program
IRFMS	Integrated Rangeland Fire Management Strategy (older link archive)
IRG	Intergovernmental Reference Guide
IRIS	Immigration Records and Identity Services Directorate (older link archive) \| Industrial Research and Development Information System (unable to verify 11/18; see archive) \| Integrated Risk Information System \| Interface Region Imaging Spectrograph (older link archive)
IRM	Bureau of Information Resource Management (changed to DT; older link archive) \| Internal Revenue Manual
IRMA	Integrated Resource Management Applications
IRMCO	Interagency Resources Management Conference (unable to verify 3/13)
IROC	Interagency Resource Ordering Capability
IRP	Intermediary Relending Program (older link archive) \| Intramural Research Program
IRPF	Infrastructure Resilience Planning Framework (older link archive)
IRR	Indian Reservation Roads (replaced by TTP; older link archive)
IRS	Indian Resources Section \| Internal Revenue Service
IRS-CI	Internal Revenue Service, Criminal Investigations (older link archive; archive2)
IRSOB	IRS Oversight Board (unable to verify 4/22)
IRTM	Division of Information Resources and Technology Management (older link archive)
IRVS	Integrated Rapid Visual Screening for Buildings (page archived; older link archive)
IRWIN	Integrated Reporting of Wildland-Fire Information (older link archive)

IS	International Services (older link archive)
ISA	Importer Self-Assessment (older link archive; archive2)
ISAs	Integrated Science Assessments
ISAC	Invasive Species Advisory Committee
ISAT	Information Sharing Assessment Tool (page archived; older link archive)
ISB	Immunization Systems Branch \| Investigative Services Branch
ISC	Integrated Support Center (changed to CSC; older link archive) \| Interagency Securities Council \| Interagency Security Committee (older link archive; archive2)
ISC3	Implementation Science Centers in Cancer Control
ISCAP	Interagency Security Classification Appeals Panel
ISCD	Infrastructure Security Compliance Division (changed to Chemical Security; older link archive; archive2; archive3; archive4)
ISCR	Institute for Scientific Computing Research (unable to verify 2/19)
ISD	Division of Indian Self-Determination \| Immunization Services Division (older link archive) \| Industry Safety Data \| Information Services Division \| Infrastructure Security Division (older link archive; archive2) \| Integrated Surface Database (replaced by GHCNh; older link archive)
ISDC	Interagency Suspension and Debarment Committee
ISE	Information Sharing Environment (unable to verify 8/22; older link archive)
ISEP	Indian School Equalization Program
ISF	Importer Security Filing
ISIS	Integrated Software for Imagers and Spectrometers (older link archive)
ISLSWG	International Space Life Sciences Working Group (unable to verify 10/23)
ISMICC	Interdepartmental Serious Mental Illness Coordinating Committee
ISMN	International Standard Music Number
ISN	Bureau of International Security and Nonproliferation (older link archive)
ISN/ECC	Office of Export Control Cooperation (also, ECC)
ISN/MNSA	Office of Multilateral Nuclear and Security Affairs (also, MNSA)
ISO	Immunization Safety Office (older link archive; archive2) \| Office of International Security Operations (unable to verify 6/19)
ISOO	Information Security Oversight Office
ISP	International Statistics Program
ISPO	International Safeguards Project Office
ISRU	In-Situ Resource Utilization
ISS	International Space Station
ISSM	Ice Sheet System Model
ISSMG	Internet and Scalable Systems Metrology Group (older link archive)
IST	Investigative Support Team
ISTAND	Innovative Science and Technology Approaches for New Drugs
I-STEP	Intermodal Security Training and Exercise Program

ITA	Interactive Tax Assistant (older link archive) \| International Trade Administration
ITAP	Federal Interagency Committee on Invasive Terrestrial Animals and Pathogens \| International Technical Assistance Program
ITAR	International Traffic in Arms Regulations
ITC	International Tax Counsel \| International Technical Cooperation \| NRCS Information Technology Center (unable to verify 11/22) \| United States International Trade Commission
ITCCH	Intramural Targeted Climate Change and Health
ITCR	Informatics Technology for Cancer Research
ITD	International Trade Division (changed to IAD)
ITDS	International Trade Data Systems
ITEC	Interagency Trade Enforcement Center (replaced by ICTIME)
ITF	Infrastructure Task Force \| Innovation Task Force
ITIL	Interdiction Technology and Integration Laboratory
ITIS	Integrated Taxonomic Information System
ITK	Information, Translation, and Knowledge-Delivery
ITL	Information Technology Laboratory
ITPO	Innovative Technology Partnerships Office (changed to SPO)
ITR	Innovation, Technology, and Research Hub
ITRDB	International Tree-Ring Data Bank
i-Tree	Individual Trees
ITS	Identity Theft Supplement (older link archive) \| Institute for Telecommunications Sciences (older link archive) \| Intelligent Transportation Systems \| International Treasury Services
ITVERP	International Terrorism Victim Expense Reimbursement Program (older link archive; older link archive)
IV&V	Katherine Johnson Independent Verification and Validation Facility (older link archive)
IVLP	International Visitor Leadership Program
IVP	International Visitors Program
IWAAs	Integrated Water Availability Assessments (older link archive)
IWCAL	Integrated Water Chemistry Assessment Laboratory
IWCG	Integrated Water Cycle Group (older link archive)
IWG	Interagency Working Group
IWG-FI	Interagency Working Group on Facilities and Infrastructure
IWG-OCM	Interagency Working Group on Ocean and Coastal Mapping
IWG-OEC	Interagency Working Group on Ocean Exploration and Characterization
IWGOA	Interagency Working Group on Ocean Acidification (older link archive)
IWGYP	Interagency Working Group on Youth Programs
IWM	Office Integrated of Waste Management (unable to verify 6/24)
IWMS	Irrigation and Water Management Survey
IWRSS	Integrated Water Resources Science and Services
IWS	Irregular Warfare Support Program (unable to verify; likely changed to CTTSO)
IWTSD	Irregular Warfare Technical Support Directorate
IXPE	Imaging X-ray Polarimetry Explorer
IYFC	Institute of Youth, Family, and Community (older link archive; archive2; archive3; archive4)
IYSC	Indian Youth Service Corps Program