The St. Louis Brown Stockings were a professional baseball club based in St. Louis, Missouri, from 1875 to 1877, which competed on the cusps of the existences of two all-professional leagues—the National Association (NA) and the National League (NL). The team is the forerunner of, but not directly connected with, the current St. Louis Cardinals Major League Baseball team. After the conclusion of the 1877 season, a game-fixing scandal involving two players the Brown Stockings had acquired led the team to resign its membership in the NL. The club then declared bankruptcy and folded.

The National Association of Professional Base Ball Players (NAPBBP), often known simply as the National Association (NA), was the first fully-professional sports league in baseball. The NA was founded in 1871 and continued through the 1875 season. It succeeded and incorporated several professional clubs from the previous National Association of Base Ball Players (NABBP) of 1857–1870, sometimes called "the amateur Association". In turn, several NA clubs created the succeeding National League of Professional Baseball Clubs, which joined with the American League of Professional Base Ball Clubs to form Major League Baseball (MLB) in 1903.