Initially part of the "corps de ballet" at NYCB, Farrell soon moved on to dancing featured roles. The first ballet choreographed for her was "Passage", now "Arcade", by John Taras in 1963. Balanchine first paired her with Jacques d'Amboise to choreograph his "Meditation", which debuted in December 1963. One of her most notable roles was Dulcinea in Balanchine's "Don Quixote", which premiered in May 1965; Balanchine's creation of that ballet was thought to be a to his newest "muse", and Balanchine performed in the role of Don Quixote on opening night. In 1968, he cast her as the lead in the "Diamonds" section of his three-act plotless ballet "Jewels".