[2] There are approximately 6,200 participating chapters in several countries, each of which is run by the students but supervised by an advisor or sponsor, usually a school teacher.

[1] At the time, Alexander Harley was the band director and Music Department Chairman at Maine Township High School East in Park Ridge, Illinois.

Harley, along with his wife Frances began formulating a plan; they decided that the initiates should be among the finest technical and academic musicians at the high school.

For almost twenty years this organization worked to promote the values of service to the music program, the school, and the community.

TRI-M continues to promote the ideals of service to the school music program, the school-at-large, and the community.

Throughout the years, there have been many ways that individuals and chapters can be recognized for their accomplishments to both Tri-M and their local school: To be eligible for membership, a student must maintain an A average in their music classes, a B average in all of their academic courses, be presently enrolled in a music course at their school, and be recommended for membership by their school's music faculty.