The acronym WSI may refer to:
- World Sindhi Institute - a human rights organization based in Washington DC, United States
- Wafer-scale integration - a future silicon chip design for super computers
- Wall Street Institute - multinational English-instruction school
- Web Services Interoperability - Organization (WS-I), computer industry consortium
- Western Sydney Institute of TAFE - college institute in New South Wales
- Winter Soldier Investigation - media event on 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
- Weather Stress Index - a relative measure of weather conditions
- Weather Services International - a subsidiary of The Weather Channel, specializes in weather data and software.
- Wrimare School Inc. - a Private school in Obando, Bulacan, Philippines.