ISF may stand for: Science and technology Interstitial fluid Imaging Science Foundation Incremental sheet forming Information Security Forum, an international information security best practices organization Ingenieurs Sans Frontieres (Engineers Without Borders) Ink Serialized Format, a vector image file format from Microsoft Israel Science Foundation Education Idries Shah Foundation, educational charity Independent Schools Foundation Academy, private international school in Hong Kong Insaf Student Federation, it is the largest Center-Left Student organization in the Nation and the official student wing of the Pakistan Tehreek-e-Insaf political party International School of Florence International School Sport Federation, sports governing body for high school sport Internationale Schule Frankfurt Rhein-Main Sport International Snowboard Federation International Softball Federation International Skyrunning Federation, world sports governing body for skyrunning International Socca Federation, governing body of small-sided-football International Sumo Federation, governing body for amateur sumo Other Importer Security Filing Impôt de Solidarité sur la Fortune, a French wealth tax International Seafarers' Federation, former international trade secretariat Idaho Shakespeare Festival, theater company Île Sans Fil, a community wireless network based in Montreal, Canada Internal Security Forces, of Lebanon Iraqi security forces Lexus IS F Italian Strategic Fund