Unlike her later film "My Fair Lady", Hepburn sings the songs herself in this, her first musical. She performs one solo, "How Long Has This Been Going On?"; a duet with Astaire, "'S Wonderful"; a duet with Kay Thompson called "On How to Be Lovely"; and takes part in an ensemble performance of "Bonjour, Paris!". Her previous dance training is also called into play, not only in the two dance numbers she performs with Astaire but also for a Bohemian-style solo dance in a nightclub, which has since often been replayed in retrospectives of her career.