Northgate High School (NHS) is a public high school located in the suburban Northgate neighborhood of Walnut Creek, California, United States. The most recent of five high schools in the Mount Diablo Unified School District, the school was built in 1974, and is home to approximately 1,500 students from Walnut Creek and Concord, California, grades 9–12. Its name derives from its location at the north entrance of Mount Diablo State Park.

Walnut Creek is a city in Contra Costa County, California, United States, located in the East Bay region of the San Francisco Bay Area, about 16 miles east of the city of Oakland. Walnut Creek has a total population of 70,127 per the 2020 census, is located at the junction of the highways from Sacramento and San Jose (I-680) and San Francisco/Oakland (SR-24), and is accessible by BART. The city shares its borders with Clayton, Lafayette, Alamo, Pleasant Hill, and Concord.