The acronym WSI may refer to:
Wafer-scale integration, a technique for building large integrated circuits Wall Street Institute, the former name of Wall Street English, an English language education company Walter Schottky Institute, a research center at the Technical University of Munich Water Safety Instructor, a person qualified to teach swimming lessons Weather Services International, a sister company to The Weather Channel, specializing in weather data and software Weather Stress Index, a relative measure of weather conditions Web Services Interoperability, Organization (WS-I), computer industry consortium Western Sydney International Airport – the IATA code of an airport in Sydney Western Sydney Institute of TAFE, college institute in New South Wales Whole-Slide Image/Imaging, in biology it is a technology to digitally scan and archive whole slides in high resolution Winter Soldier Investigation, inquiry into war crimes resulting from United States policies in the Vietnam War Wojskowe Służby Informacyjne, Poland's former military intelligence services World Security Institute, think-tank for independent research and journalism on global affairs World Sindhi Institute, a human rights organization based in Washington, D.C., United States Writers and Scholars International, Ltd, the London-based organisation that publishes the Index on Censorship