Gunston Hall School was an American private women's finishing school located in Washington, D.C. It was established by Beverley Randolph Mason and his wife in 1892. The school closed in 1942 due to World War II.

Beverley Randolph Mason and his wife, Elizabeth Harrison Nelson, started Gunston Hall School for Girls in 1892. They founded the school because they were not satisfied with the educational opportunities for girls in Washington D.C. at the time. It was named for Gunston Hall, the historic house of George Mason, Beverly Mason's great-grandfather.

The purpose of Gunston Hall School was to "train students to be intellectually mature, physically fit, socially well adjusted and to give them a basic faith in God that will steady and support them all their lives". The school's first students were Mason's children and children from their neighborhood. The Masons were jointly the school's principals. Mason previously taught at the United States Military Academy in West Point and was a mathematics teacher and Latin teacher at the Norwood Institute.

Originally, Gunston Hall School was operated from the Mason home at 3017 O Street in the Georgetown neighborhood of Washington, D.C. In 1900, the school moved to Thomas Circle, before moving to 1904 Florida Avenue N.W. in 1906 where it remained until it closed. The latter location had more classroom space and accommodations for boarding students. By 1905, Gunston Hall School had eight resident teachers and twelve visiting teachers. Day students were transported by private conveyance provided by the school.

For the 1911–1912 academic year, the school had fifty students and 27 teachers. Its younger students wore sailor blouses with wool jumpers, black stockings, and black buttoned shoes; the older students wore shirtwaists and silk petticoats. Tuition and board were $750 to $800 for the year, depending on the room. Students had to provide two sets of sheets and twelve dinner napkins for their use. Added fees included $2 to use the tennis courts and $25 to use the piano for daily practice.

Beverly Mason died in April 1910. Josephine Mason, daughter of the school's founders, taught at Gunston Hall School after graduating from college and before her marriage in 1916. Her brother, Richard Nelson Mason, also taught at the school, served as its business manager, and later became its principal until he died in 1940. By 1927, Gunston Hall School was the second oldest private school in Washington, D.C. Its principal was Mary L. Gildersleeve. The school started a new pre-academic program in 1927, providing day school classes for grades kindergarten through eight.

In the 1930s, Gunston Hall ranked "among the highest 'culture school' for girls in the United States". In June 1942, the school's commencement speaker was Harry S. Truman, whose daughter Margaret was graduating. The then senator's speech was part of the school's 50th anniversary celebration. However, Gunston Hall School closed in 1942 because of a shortage of teachers, resulting from World War II.

After the school closed, the recently widowed Josephine Mason Easley moved there; it remained her home until she died in 1962.