Marymount School opened its doors on February 2, 1926 with thirteen students. The School was housed in only the 1028 building, and the first graduates were Elizabeth Byrne and Marjorie McCormack in 1928.
Despite low enrollment after the Great Depression, Marymount expanded both its academic program and its physical plant. Mother Butler purchased the Pratt Mansion (1027) in 1936 and established a Junior College.
Mother Butler’s death in 1940 and the impact of WWII took its toll on morale. The RSHM school network expanded in 1946 with the founding of Marymount Rome, and the Junior College spun off into Marymount Manhattan College in 1948.
Marymount expanded into the Dunlevy Millbank mansion (1026) in 1950 but was plagued by construction setbacks. The math/science program flourished and many extracurricular clubs and social events were established.
Changing political and social landscapes were reflected at Marymount in the 1960s. AP courses and social justice were added to the curriculum. The first Board of Trustees met in 1969.
Marymount became NYSAIS accredited in 1973, and the School was restructured so Lower School housed Nursery-VI and Upper School housed VII-XII. Sr. Kathleen Fagan became Headmistress in 1976.
The 1980s were a time of great growth at Marymount, with the construction of the rooftop gym in 1984 and the establishment of the Middle School division for Classes IV-VII in 1989.
Marymount opened its science labs in 1994 and formalized its technology plan for the School. The athletics program flourished in the 1990s and Marymount established diversity initiatives to foster cultural awareness.
Marymount opened the Middle School building at 2 East 82 Street in 2002, while renovations at Fifth Avenue expanded the art/science programs. Concepcion Alvar became the first lay Headmistress in 2004.
Marymount added 42,000 square feet in 2010 by leasing 116 East 97th Street for athletics, art, and science facilities. The School acquired a vacant lot on the same block in 2012 for the “School of the Future.”