[2] Formed in 1946, the MPSSAA is made up of public high schools from each of Maryland's 23 counties and independent city of Baltimore, which joined the association in 1993 when its public high schools withdrew from the earlier longtime athletic league, the Maryland Scholastic Association (MSA) which was founded in 1919.

After the Baltimore City public high schools withdrew from the MSA, the remaining private/religious/independent schools conferred and organized two parallel regional/state-wide athletic leagues with sports competition and exercise activities with one for young men and the other for young women.

All public high schools in Maryland in the 23 counties who qualify under the established rules and regulations may become members of the MPSSAA.

The stated purpose of the MPSSAA is "to promote, direct, and control all interscholastic activities of high school students; to establish, maintain, and enforce regulations to assure that all such activities are part of and contribute toward the comprehensive educational program of the state of Maryland; to work with the state department of education in the development of the program to safeguard the physical, mental, and moral welfare of high school students and protect them from exploitation.

MPSSAA member schools compete within geographic regions (jurisdictions) and are divided into leagues across the state.