The Washington Nationals are an American professional baseball team based in Washington, D.C. The Nationals compete in Major League Baseball (MLB) as a member of the National League (NL) East Division. From 2005 to 2007, the team played in RFK Stadium while a new stadium was being built. In 2008, they moved to Nationals Park, located on South Capitol Street in the Navy Yard neighborhood of the Southeast quadrant of D.C., near the Anacostia River.

The National League of Professional Baseball Clubs, known simply as the National League (NL), is the older of two leagues constituting Major League Baseball (MLB) in the United States and Canada, and the world's oldest extant professional team sports league. Founded on February 2, 1876, to replace the National Association of Professional Base Ball Players (NAPBBP) of 1871–1875, the NL is sometimes called the Senior Circuit, in contrast to MLB's other league, the American League, which was founded 25 years later and is called the "Junior Circuit". Both leagues currently have 15 teams.