[1] A local historian states that ADHS opened in 1875,[2] although a cornerstone on the building bears the date 1876.

An early and illustrious ADHS student was James Naismith, the inventor of basketball.

The Almonte Thunderbolts won OFSAA basketball with their senior team during the 2018-19 season.

The SchoolBOX charitable organization was created by ADHS alumnus Tom Affleck.

SchoolBOX builds schools for children in Central America, and many of its volunteers are ADHS students.