Grades 7-12 are housed in the Upper School Building. Average class size is 15 students.

Brentwood School Honor Code Grades 7-12
The chief purpose of Brentwood's Honor Code is to create and maintain within each member of the Brentwood community the proper attitude towards honor and honorable living, so that throughout one's daily activities and interactions, a spirit of fair play and truth is encouraged, while dishonorable conduct is not tolerated.

To accomplish the mission of the Honor Code, every member of the Brentwood community pledges to follow and uphold the Honor System's four guiding principles:

I will not lie.
I will not cheat.
I will not steal.
I will not plagiarize.
I will not tolerate any dishonorable behavior on behalf of myself or others.

The Honor Pledge, a reminder and reaffirmation of student awareness of honor, is the most visible part of the Honor Code. "On my honor as a Brentwood student, I pledge that I have neither given nor received any assistance on this assignment."