The Philadelphia Keystones (also known as the Keystone Club of Philadelphia) were a professional baseball franchise. In 1884, they were a member of the short-lived Union Association. The team was owned by former player Tom Pratt. Like several other teams in the Union Association, the Keystones did not make it through the entire season, folding after the game of August 7. The entire league ceased operations after 1884, its first and only season.