WPI may refer to:
Organizations Whittemore Peterson Institute, performs research into chronic fatigue syndrome Worcester Polytechnic Institute, a private research university in Worcester, Massachusetts, US Worker-communist Party of Iran, a political party Workers' Party (Ireland), two political parties Workplace Policy Institute, a lobbying organization operated by law firm Littler Mendelson
Other uses Whey protein isolate, a dietary supplement created by filtering milk protein Wholesale price index, the price of a representative basket of wholesale goods Work Personality Index, a psychometric assessment Wraps per inch, a measure of thickness of yarn
See also Derwent World Patents Index (DWPI)