Partner Leagues


The American Association, Atlantic League, Frontier League and Pioneer League are professional baseball leagues that have been designated as Partner Leagues of Major League Baseball.

These leagues collaborate with MLB on various initiatives while providing organized baseball to communities throughout the United States and Canada, and also expanding the geographic reach of the game. The leagues provide development opportunities for young players throughout the country and for veteran players who seek a second chance to reach the Major Leagues. Partner Leagues also provide formal, MLB-sponsored programs to give people with diverse backgrounds additional playing and coaching opportunities.

The American Association consists of 12 member clubs situated in the Midwest and covering nine states (Illinois, Indiana, Iowa, Kansas, Nebraska, North Dakota, South Dakota, Texas and Wisconsin) and one Canadian province (Manitoba). Formed in 2006, the American Association offers fans of the league its owned and operated video streaming service, which carries all games in the league’s 600-game schedule. American Association games can also be watched coast to coast on various OTA, OTT and Linear channels. In addition to vying annually for the Miles Wolff Cup championship trophy, the league champion also qualifies for the World Baseball Softball Confederation Champions League tournament. The American Association plays a 100-game regular season from May through Labor Day. For more information, visit

The Atlantic League has been a leader in baseball innovation and has sent over 1,400 players to MLB organizations. In 2019, MLB and the Atlantic League entered a partnership to experiment with new rules and equipment. The partnership allowed MLB to explore pace of play and other initiatives, additional uses of the pitch clock, a three-batter minimum for pitchers, the restriction of infield shifts on hitters, automated balls and strikes, 18” bases, and other initiatives that have reimagined Baseball and impacted the Major Leagues. The 10-team league competes in a 126-game schedule from late April through mid-September and spans across six states including Kentucky, Maryland, New York, North Carolina, Pennsylvania, and West Virginia. For more information, visit

The Frontier League is the largest Partner League, consisting of 16 teams that stretch across eight U.S. states including Illinois, Indiana, Kentucky, Massachusetts, New Jersey, New York, Ohio and Pennsylvania, and two Canadian provinces (Ontario and Quebec). Formed in 1993, the Frontier League added five clubs from the former Can-Am League following the 2019 season and remain one of two Partner Leagues with international connections. The Frontier League has placed more than 1,000 players in Major League organizations, with over half of those players getting their first start in pro ball in the Frontier League. In 2021, the Frontier League began play as a Partner League of MLB. The 96-game season takes place from May through September. For more information, visit

Since 1939, the Pioneer Baseball League had operated in the Mountain West region as an MLB-affiliated league. Beginning in 2021, the Pioneer League became a Partner League with clubs in Montana, Idaho, Utah, Colorado and California. The Pioneer League is a player development league, with players having less than three years of professional experience. The PBL is focused on innovation and experimental rules, having initiated the shootout style “Knockout Round” to replace extra innings, designated pinch hitters and pinch runners, and other cutting-edge rules. The PBL has a 96-game slate from mid-May through mid-September. For more information, visit