The peer-based, Philadelphia-based non-profit association was founded in 1887.

It is a voluntary organization that performs peer evaluation and regional accreditation of public and private schools (including parochial / religious-owned and independent secular schools).

[1] The two Middle States Association Commissions on Elementary and Secondary Schools (M.S.A.-C.E.S.S.)

as of 2021[update] accredit nearly 2600 public and private schools of elementary and secondary / high schools, along with the various school systems / districts of cities / towns and counties throughout the United States (especially in its originally designated Middle Atlantic states region) and those of American origin in more than 100 other countries around the world.

[2][3] MSA used to accredit colleges and universities through its higher education commission.