William Fremd High School, or Fremd, is a public four-year high school located in Palatine, Illinois, a northwest suburb of Chicago, Illinois, in the United States. It is part of Township High School District 211, which also includes James B. Conant High School, Hoffman Estates High School, Palatine High School, and Schaumburg High School. Academically, Fremd High School has also been recognized by Newsweek as one of "America's Best High Schools" and by U.S. News & World Report as one of 99 outstanding high schools in the United States with the average AP test taker in the class of 2018 taking 5.4 exams. Fremd serves the portion of Palatine that is southwest of the UP NW Line railroad tracks as well as north Hoffman Estates, west Rolling Meadows, north Schaumburg, east South Barrington and southeast Inverness. Feeder schools include Plum Grove Junior High, Carl Sandburg Junior High, Walter Sundling Junior High and Margaret Mead Junior High. Feeder elementary schools are Pleasant Hill, Paddock, Hunting Ridge, Central Road, Willow Bend, Thomas Jefferson, Marion Jordan, Fairview, and Frank C. Whiteley.

The Illinois High School Association (IHSA) is an association that regulates competition of interscholastic sports and some interscholastic activities at the high school level for the state of Illinois. It is a charter member of the National Federation of State High School Associations (NFHS). The IHSA regulates 14 sports for boys, 15 sports for girls, and eight co-educational non-athletic activities. More than 760 public and private high schools in the state of Illinois are members of the IHSA. The Association's offices are in Bloomington, Illinois.