If approved, the association's Legislative Council would have to vote again in February for the ban to become final.
A high school principal from northeast Mississippi made the proposal, saying private schools have an unfair advantage in recruiting students.
"Among the coaching community, there's felt to be a lot of discrepancies over who can transfer and when they're eligible," said Smithville High School Principal Chad O'Brian. His proposal to ban private schools at the end of the current two-year classification was passed 40-3 at a district meeting in northeast Mississippi during the summer.
O'Brian said that when his school played Greenville's St. Joseph Catholic School in the baseball playoffs last year, some of that school's players lived in Arkansas.
"They play for the Mississippi High School Activities Association," O'Brian said. "I think by name and definition, it's unfair."
Clinton-based MHSAA sponsors 16 sports, plus competitions for debate, music, drama and speech. It includes 265 high schools and about 350 middle schools. Private school members of the association say they follow its rules, which assign them a 20-mile radius as their home district, and force students from outside that zone to sit out a year.
"We turn in the same paperwork," said Tupelo Christian Preparatory School Athletic Director Aubrey Boren, "We fill out the same forms."
Of other southern states, only Virginia bans private schools from its public high school league, although many states have competing private-school associations. Officials with the National Federation of State High School Associations said they didn't have a count of how many public school leagues allowed private members nationwide.
Private schools have had a lot of success in MHSAA, with Tupelo Christian winning the all-sports award given by The Clarion-Ledger at the 1A level last year, the smallest of six size classes. Likewise, Madison's St. Joseph Catholic High School won in 2A and Ridgeland's St. Andrew's Episcopal School won in 3A.
"Any time you win, people are always going to watch you more closely," said Stace McRaney, athletic director at St. Stanislaus in Bay St. Louis.
Most private schools in Mississippi are members of the separate Mississippi Association of Independent Schools. McRaney and Boren said their schools don't want to play in MAIS because they would have to travel long distances for many games.
"It would be a blow for a school like us," McRaney said. "There's really nobody to play in our area."
Boren also noted that MAIS is also an accrediting body, which means his school would be academically regulated by that association.
Despite the big vote O'Brian won in northeast Mississippi, it's not clear if the measure will pass.
"I haven't seen a lot of groundswell for it that's definitely going to push it through," McRaney said.
Here's a list of the 13 private schools that are currently members of the Mississippi High School Activities Association:
Our Lady Academy, Bay St. Louis (girls only)
St. Stanislaus, Bay St. Louis (boys only)
St. Patrick, Biloxi
Sacred Heart, Hattiesburg
St. Aloysius, Vicksburg
St. Joseph, Madison
St. Joseph, Greenville
St. Andrew's, Ridgeland
Tupelo Christian Preparatory, Tupelo
French Camp Academy, French Camp
Piney Woods School, Piney Woods