The Harker School is a private, co-educational, non-profit college preparatory school in San Jose, California, United States. Founded in 1893 as Manzanita Hall by Frank Cramer in Palo Alto, Harker now has four separate campuses: Bucknall, Blackford, Union and Saratoga, named for the streets on which they lie. Bucknall is the Lower School campus, educating kindergarten through grade 5. The Middle School, grades 6 to 8, is on the Blackford campus, the Upper School, grades 9 to 12, is on the Saratoga campus and the Preschool, Ages 3–5 is on the Union campus.

The current Harker administration is led by Christopher Nikoloff, who succeeded Howard and Diana Nichols following their retirement after the 2004–05 academic year. Howard Nichols was the son of Major Donald L. Nichols, who created the present day Harker School by merging the Palo Alto Military Academy in Palo Alto (as Manzanita Hall was then called) with Harker Day School in 1972 and moving to the Saratoga campus. The Upper Division is led by Butch Keller, the Middle Division by Cindy Kerr Ellis, the Elementary Division by Kristin Giammona, the Primary Division by Sarah Leonard and the Preschool Division by Kelly Espinosa.