[12] Garrison Forest was established by Mary Moncrieffe Livingston (1869-1956), the head of a day school in Kingston, New York, in 1910.

[13][2] The school she set up was located in a house off of Reisterstown Road in the Green Spring Valley Historic District.

[21][18] Aggie Underwood served as headmistress from 1978-1989; Alexander Uhle was interim headmaster from 1989-1990; and Midge Bowman held this role from 1990-1994.

[3] Many of the academic and supplemental activities and programs at GFS center on the natural world, lab science, and community engagement.

[34] During World War II, students at Garrison Forest started the Service League, a student-led community outreach program.

[35][36][37] Since 2005, the GFS faculty, staff, and administrators have sponsored a Habitat for Humanity house in Baltimore, an annual project that grew out of the school's initial reaction to Hurricane Katrina.

[citation needed] GFS also offers the Jenkins Fellow program, a summerlong service project fellowship that can take place in the United States or abroad.

[4] Seventh graders at the Middle School participate in a Shark Tank-inspired group project where they create and pitch innovative ideas.

"[39] The 25-student Middle School chorus was invited by the Distinguished Concerts International New York to perform at Carnegie Hall in 2016 in as part of a 200-person choir.

"[49] A cow pasture on campus was converted into a hockey field; in its early days, before GFS had other teams to play, students competed with faculty.

The school also participates in equestrian sports such as equitation, showjumping, and eventing, in addition to their championship polo team.

[46][52][9] As such, GFS polo players compete against both co-ed and male teams from high schools, colleges, and local clubs.

[54][6][55][5] At graduation, students wear white formal clothing and are given a bouquet of ragged-robins, the school flower, to carry during the commencement ceremony.