The Philadelphia Athletics were a professional baseball team, one of six charter members of the American Association, a 19th-century major league, which began play in 1882 as a rival to the National League. The other teams were the Baltimore Orioles, Cincinnati Red Stockings, Eclipse of Louisville, Pittsburgh Alleghenys, and St. Louis Brown Stockings. The team took its name from a previous team, which played in the National Association from 1871 through 1875 and in the National League in 1876.

The American Association of Base Ball Clubs (AA) was a professional baseball league that existed for 10 seasons from 1882 to 1891. Together with the National League (NL), founded in 1876, the AA participated in an early version of the World Series seven times versus the champion of the NL in an interleague championship playoff tournament. At the end of its run, several AA franchises joined the NL. After 1891, the NL existed alone, with each season's champions being awarded the Temple Cup (1894–1897).