The Mackellar Girls Campus of Northern Beaches Secondary College is a government-funded single-sex comprehensive secondary day school for girls only, located in Manly Vale, a suburb on the Northern Beaches of Sydney, New South Wales, Australia. Established in 1968 as Manly Vale High School, and then became Mackellar Girls High School, named in honour of Dorothea Mackellar, the school caters for approximately 1,200 students from Year 7 and Year 12. The school is operated by the New South Wales Department of Education; the principal is Christine Del Gallo.