[1] As of 2023, the enrolled student body race/ethnicity was self reported as 7.4% African American, 16.0% Asian, 12.9% Hispanic, 53.3% White, and 10.3% Multi-ethnic.

Instruction began on August 17, 1843, on the lower floor of the Town Hall on Walnut Street, which was described by a former student as a "dismal, damp and dark room...not unlike a tomb".

[2] In fall 1895, the third and present location of Brookline High School opened as Shailer Hall, a new three and a half story brick structure with a pitched roof designed by architects Andrews, Jaques and Rantoul.

[7] In early 2022, Brookline High School opened a new building on 22 Tappan Street, designed primarily to house freshmen.

[12] As of 2021, Brookline High School was ranked 64th nationally for STEM (Science, Technology, Engineering and Mathematics), according to U.S. News & World Report.

[17][18] Brookline High School features the largest interscholastic athletics program in New England, with 71 teams in 40 sports.

[19] Some of the atypical sports include squash, curling, golf, ultimate disc, crew, sailing, water polo, and rugby.

The most popular athletics program at Brookline High School, as of 2017, is ultimate disc with over 110 students participating.

[29] The Cypress, formerly The Sagamore, is a school-affiliated newspaper published monthly by students of Brookline High School.

[31] Over the past few years, the paper has publicized and discussed issues in and around the school, including racism and teenage pregnancy.

In 2011, New England Scholastic Press Association awarded The Sagamore "Highest Achievement" in Newspaper Class I category.