The Horace Mann School seal was originally devised in 1958 by Norman H. Bonter, then Director of Development. The image that he proposed to the school’s Community Council featured three key symbols:
- A white chevron, reminiscent of HM’s earlier connections to Columbia University;
- A lion, from the Mann family coat of arms;
- And a background of maroon, the school color.
An article in The Record in 1959 reported that "the shield should provide the answers to two long-debated problems: creating a uniformity of dress in such organizations as the band, glee club, and the debating society; adopting an HM mascot. Such a mascot would take active part in the cheerleading and the band performances at sporting events. The central figure of the shield, the lion…will provide the basis for a striking emblem to be affixed on school blazers and supplies."
Bonter first discussed the adoption of such a shield with headmasters of several schools and several "heraldry experts," said The Record in ’59. After the idea was debated at a Council meeting, it was then distributed to 26 advisories, where it was met with an approval of 22 to four. In order to excite enthusiasm from students, the seal was additionally discussed during an assembly.
The lion mascot took on a new role when the Class of 2002 dedicated the lion sculpture outside Fisher Hall. “New York sculptor Carter Jones interpreted the lion as an 'adolescent' animal, poised on the verge of achieving its adult potential, much like the students at this school,” said a Record article in 2002. Currently, the shield appears only slightly different from its original depiction, having undergone minor modifications. The most recent version of the shield first appeared in the September 7, 1990 issue of the Record, with the chevron eliminated and the school initials, "HM," located above the lion. Today, the emblem continues to show up in a variety of places, including stationary, assignment planners, athletic attire, notebooks, and chairs.