Horace Mann School students have come from all neighborhoods in Boston, and reflect the diversity of the city itself. In the early years of the school, parents of students are recorded as being born locally in states throughout New England, and abroad in countries such as Ireland, England and Germany. In the early 20th century, countries of origin begin to include Italy, Russia, Sweden, Spain, and Denmark. Students of color occasionally appear in the student register and school photographs from 1879 onwards, notable at a time when education was still very much segregated.
Some of these students were from families of very modest means, and a parent association called the Boston Educational Association for Deaf Children raised funds to provide transportation fare for those who could not afford it. They also organized home visits to meet with the student's parents and gain an understanding of the student's home environment. As today, some of the students' parents were recent immigrants who did not speak English. The variety of cultural backgrounds and life experiences represented in the student body make it a rich reflection of the population of Boston from 1869 to this day.