Westfield High School is a public high school in unincorporated Fairfax County, Virginia, United States, west of the Chantilly CDP. 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. Opened in 2000, it is the head of the Westfield High School Pyramid in Cluster VIII. Westfield's main building has the same layout as South County High School (Fairfax County, Virginia). At 3,260 students, it is one of the largest four-year high schools in the Commonwealth of Virginia.