ISI
- Béla H. Bánáthy
- IS1 (disambiguation)
- ISI mark
- Ice Skating Institute
- Image Space Incorporated
- ImageSat International
- Import substitution industrialization
- Independent Schools Inspectorate
- Indian Standards Institute
- Indian Statistical Institute
- Indonesian Institute of the Arts, Denpasar
- Indonesian Institute of the Arts, Surakarta
- Indonesian Institute of the Arts, Yogyakarta
- Information Sciences Institute
- Information Sharing Index
- Infrared Spatial Interferometer
- Institute for Scientific Information
- Institute for Scientific Interchange
- Integral Satcom Initiative
- Integrated Systems, Inc.
- Inter-Services Intelligence
- Intercollegiate Studies Institute
- International School Ibadan
- International School of Iceland
- International Sensitivity Index
- International Statistical Institute
- Interstimulus interval
- Intersymbol interference
- Iron and Steel Institute
- Isi (name)
- Isi (song)
- Isis (disambiguation)
- Islamic School of Irving
- Islamic State of Iraq
- University Grants Commission (Bangladesh)
- İsi