Minor leagues in the sense intended in this article are professional sports leagues which are not regarded as the premier leagues in those sports. Minor league teams tend to play in smaller, less elaborate venues, often competing in smaller cities. This term is used in North America with regard to several organizations competing in various sports.

The most famous minor league organization is in baseball. Minor league baseball is almost as old as the professional game itself, and at first consisted of attempts to play baseball in smaller cities and towns independent of the National League, the first true major baseball league. Soon, scouts for the National League were travelling to watch minor league teams play and attempting to sign the more talented ones away. Some sports historians cite the connection between the other major league, the American League and its minor league forebear, the Western Association. Soon Major League Baseball began formal developmental agreements with some minor league teams, while others remained independent. The most prominent independent minor baseball league today is probably the Northern League.

Baseball is not the only sport with minor leagues. In fact all of the prominent team sports have them. The sport with the next most extensive system of minor leagues other than baseball is ice hockey. The American Hockey League is the most prominent of these, with most NHL teams having a "farm" team in the AHL where they develop young players and occasionally rehabilitate older players who are injured or whose quality of play has slumped. These teams in turn have lower-level minor leagues to draw players from and pass players down to. Junior and Senior hockey leagues are similar, but not exactly equivalent, to minor leagues due to their age and experience restrictions.

The National Basketball Association has an affiliated minor league, the National Basketball Development League. Additionally, the Continental Basketball Association has served some of the purposes of a minor league for the NBA for many years. However, there are no direct developmental agreements between CBA and NBA teams the way that there are between Major League Baseball and National Hockey League teams and their minor league affiliates.

While there are various semi-professional football leagues, none have any affiliation with the National Football League. Its only "official" developmental minor league is NFL Europe. Many consider the Arena Football League to be a minor league, but this is not exactly the case. While the NFL now allows its owners also to own Arena teams, the games are considerably different, and the AFL has aspirations to be a major league in its right, and has its own minor league, af2.

Other sports organizations considered to be minor leagues are the golf Nationwide Tour, affiliated with the PGA Tour, NASCAR's Busch Series and various other affilated satellite tours of other individual sports.

See also: List of developmental and minor sports leagues