Horace Mann was born in 1796. He played a leading role in establishing the elementary system in the U.S. After graduating from Brown University, he went on to be a member of the Massachusetts state legislature. In 1848, he won a seat in the House of Representatives, in which capacity he was a fervent advocate of public education. He was the President of Antioch College from 1853 until his death in 1859. Although Horace Mann was one of the most well-known proponents of mandatory public school education in America, he did not have anything to do with the founding of the school in Riverdale, New York that bears his name.

The Horace Mann School was actually founded by Nicholas Murray Butler as a co-educational experimental and developmental unit of Teachers College, Columbia University. First opening its doors in 1887 at 9 University Place in Manhattan, the school's first students were two sets of siblings. Three years later, the school added a secondary divison, and a year after that, it added a college preparatory division, which charged $150 as a full year's tuition for a high school senior. The school moved up to 120th Street in Morningside Heights in 1901, at a time when few large buildings were in that area and geese and goats (pets of the numerous squatters) still roamed freely around the empty lots. [Go to a page of pictures of the 120th Street site and its occupants.] The school was across the street from the Bloomingdale Insane Asylum (which had been deserted shortly before the school's arrival), which also served housing for the students at Teachers College. The building, however, was state-of-the-art, thanks to a donation from Mr. and Mrs. V. Everit Macy, and included electricity and an imposing statue of Athena in the front hallway. Columbia University, to which Horace Mann was still closely tied, moved from their Manhattan campus up to their present location at 116th Street shortly after Horace Mann had made the transition. By this time, however, Horace Mann was becoming less of a experimental school for the students of Teachers College to try out their new ideas, and more of a well-recognized school in its own right. Teachers College eventually created the Lincoln School as a new co-educational school in which to practice their experimental teaching methods, leaving Horace Mann more and more independent.

The Boys' School, which is at the school's current location at 246th Street in the Riverdale section of the Bronx, is reported to have cost $20,001 to purchase in 1909. The $20,000 paid for the property itself; Virgil Prettyman, Headmaster from 1894 to 1920, had trouble finding the location and asked a local homeless man in Van Cortlandt Park how to get to the site. The man showed him the way in exchange for a $1 quart of hard apple cider. The Girls' School, which separated from the Boys' School in 1914, continued at its 120th Street location until 1940, when it merged with the Lincoln School. In 1946, the merged school closed, leaving Horace Mann to became financially and administratively separate from Teachers College and an independent day school for boys in grades 7-12. Horace Mann's final charter from the New York Board of Regents was granted in 1951. The re-establishment of co-education was accomplished through mergers with several other schools; the New York School for Nursery Years (founded in 1954 and housed in Andrew Carnegie's old carriage house on 90th Street) became the Horace Mann School for Nursery Years in 1968, the Barnard School (founded in 1886) became the Horace Mann-Barnard Lower School in 1972, and girls began to once again enroll in the Upper School in 1975. The 246th Street campus- which became the only campus after the closing of the Girls' School in 1946- also had a dormitory; until 1954, there were about fifty boarders at the Boys' School that stayed near 250th Street at 5001 Delafield Avenue, with several faculty members who lived there as well. In 1952, a new wing for the gym was added under the supervision of headmaster Dr. Mitchell Gratwick. In 1956,Pforzheimer Hall was built, named after Carl H. Pforzheimer, who was chairman of the Board of Trustees. The Pforzheimer family was also responsible for the school's swimming pool. In 1962, Alfred Gross Hall was built, which housed the Van Alstyne Auditorium and the new cafeteria. The old auditorium became the Theresa H. Loeb library. The fourth floor of the newly-renamed Tillinghast Hall (named for Charles Carpenter Tillinghast, headmaster from 1920 to 1950, and the man responsible for putting Horace Mann on the map) was converted from a gymnasium into classrooms. The Gratwick science wing was added onto Pforzheimer Hall in the early 1970's; the two sections are referred to simply as "Pforzheimer", but Gratwick is actually the red brick section of the building facing the football field.

In 1965, the John Dorr Nature Laboratory- 85 acres of land in rural Washington Depot, Connecticut- was left to the school by John Dorr, an inventor and a neighbor of Headmaster Gratwick. While much appreciated, the new gift did present a few problems:

"But it was not immediately apparent how to use the new boon. For one thing, the land was kneedeep in poison ivy, and for another there were no models of private school outdoor education programs to emulate. Gratwick, doing his homework, looked into Outward Bound, an independent wilderness eductaion course which had begun during World War II as survival training for British seamen, and decided he had found the prototype for his plan to get New Yorkers out of the asphalt jungle...Almost all the initial work of preparing the land for the school- the sawing and splitting of wood, the building of shelters, the clearing of trails and stream beds- was done by students. By 1967, the program's second year, the main lodge was built to a design by Gratwick...There was neither plumbing nor a shower, although there was an eight-seater outhouse." 

(Excerpted from Horace Mann-Barnard: The First Hundred Years, by Harold J. Bauld and Jerome B. Kissinger, copyright 1987, page 65-66.)

Today, Glenn Sheratt heads the John Dorr campus. Fourth, sixth, seventh, and eighth graders all make trips to the Nature Lab with their classmates for week-long stays.

In 1987, Horace Mann celebrated its centennial anniversary. The current Head of School is Dr. Eileen Mullady, who lives in the Hurley House across the street from the school. The Head of Upper School (grades 9-12) is Dr. Lawrence Weiss, the Head of the Middle School (grades 7-8) is Marion Linden, the Head of the Lower School (grades Kindergarten-6) is Dr. Steven Tobolsky, and the Head of Nursery Years (2 years old-Kindergarten) is Patricia Zuroski.