The American Repertory Theater (A.R.T.) is a professional not-for-profit theater in Cambridge, Massachusetts. Founded in 1979 by Robert Brustein, the A.R.T. is known for its commitment to new American plays and music–theater explorations; to neglected works of the past; and to established classical texts reinterpreted in refreshing new ways. Over the past thirty years it has garnered many of the nation's most distinguished awards, including a Pulitzer Prize (1982), a Tony Award (1986), and a Jujamcyn Award (1985). In 2002, the A.R.T. was the recipient of the National Theatre Conference's Outstanding Achievement Award, and it was named one of the top three theaters in the country by Time magazine in 2003. The A.R.T. is housed in the Loeb Drama Center at Harvard University, a building it shares with the Harvard-Radcliffe Dramatic Club. The A.R.T. operates the Institute for Advanced Theater Training.

In 2002 Robert Woodruff replaced founder Robert Brustein as the A.R.T.'s artistic director. After Woodruff's departure in 2007, Associate Artistic Director Gideon Lester filled the position for the 2008/2009 season, and, in May 2008, Diane Paulus was named the new artistic director. Paulus, a Harvard alum, is widely known as a director of theater and opera. Her work includes The Donkey Show, which ran off-Broadway for six years; productions at the Chicago Opera Theatre; and the Public Theater's 2008 production of Hair, which won the Tony Award for Best Revival of a Musical.