The original libretto was by Lillian Hellman. For the 1974 revival, a new script was written by Hugh Wheeler, and it is this script that has been used ever since. Although most of the lyrics by Richard Wilbur, the principal lyricist, remained, as well those of the other writers, director Harold Prince had Stephen Sondheim rewrite lyrics for one song and add new lyrics for several others that were never used in the original 1956 production of the show.