Westfield High School is a public secondary school in Chantilly, an unincorporated community in Fairfax County, Virginia, United States. It is a part of Fairfax County Public Schools (FCPS), serving students from the communities including Chantilly and Centreville as well as areas with Herndon addresses in grades 9–12. Westfield opened in 2000 to help deal with the extensive overcrowding at adjacent schools, primarily Centreville and Chantilly High Schools. At 3,260 students, it is one of the largest four-year high schools in the Commonwealth of Virginia, and is often criticized as grossly crowded.
The school was listed as the 46th best public high school in America by Newsweek magazine in 2002 and 27th in the Washington, D.C., metropolitan area by The Washington Post in 2006 due to a high percentage of students enrolled in Westfield's Advanced Placement (AP) classes. Westfield shares a business partnership with Northrop Grumman's business IT group that entails sharing of buildings, as well as financial donations and gifts of supplies. It also shares an education partnership with Centreville Presbyterian Church to improve student achievement. Westfield has come under scrutiny because two unrelated murders perpetrated by alumni occurred within one year.