Rev. Endicott Peabody and Richard Russell were responsible for the origin of Brooks School. Peabody was headmaster of Groton, and he started Brooks School in 1926, becoming the first president of the board of trustees. Russell was the secretary-treasurer of the board and provided the land and buildings for the school.
Reverends, parents and university graduates also contributed to the early days of the school, including the Reverend Sherrard Billings, Roger B. Merriman, the Right Reverend Charles L. Slattery, Frank D. Ashburn and James Jackson. Frank Ashburn was the first headmaster of the school and was succeeded by H. Peter Aitken, Lawrence W. Becker and, in 2008, John R. Packard. The teaching of the Episcopalian Christian community influences the education and governance of the school. The school began as an all boys school, and later incorporated girls into the classroom. Brooks School also started as a six-year school and only later became a four-year institution.
The school shield originated in 1931, as members of the school community submitted ideas for its design. The accepted design was a black cross over a white cross, accompanied by the motto “Victuri te salutamus." Phillips Brooks composed the school hymn.
As of 2015, Brooks School offers courses in science, math, theology and other subjects.