In addition to performing, Resnik worked as a stage director at several European opera houses during the 1970s and 1980s, usually in collaboration with her husband, scenic and costume designer Arbit Blatas.

[3] Resnik made her professional singing debut at the age of 22 on October 27, 1942, giving a recital of art songs at the Brooklyn Academy of Music.

[8] In February and March 1943 she sang Leonore in Fidelio and Micaela in Carmen at the Palacio de Bellas Artes in Mexico City under Erich Kleiber.

[9][10] In the spring of 1944, she portrayed both Frasquita and Micaela in Georges Bizet's Carmen in the New York City Opera's (NYCO) first season with Dusolina Giannini in the title role.

[12] In April 1944 Resnik won the Metropolitan Opera Auditions of the Air, performing "Ernani, involami", and was offered a contract with that company for the 1944/45 season.

[6] Her debut at the Met was doubly dramatic – on one day's notice she substituted on December 6, 1944, for Zinka Milanov as Leonora in Il trovatore eliciting acclaim from the public, the critics noting that all the vocal "virtuosity" and her stage presence as an actress were very impressive.

[13] During the next decade, she offered twenty heroines: Donna Elvira and Donna Anna (Don Giovanni), Fidelio, Sieglinde (Die Walküre), Gutrune (Götterdämmerung), Chrysothemis (Elektra), Rosalinda and Eboli (Don Carlos), Aida, Alice Ford (Falstaff), Tosca, Madama Butterfly and Musetta (La bohème).

During these years, her teacher was Rosalie Miller and her life began with the legendary conductors Otto Klemperer, Bruno Walter, George Szell, Fritz Reiner, William Steinberg and Erich Leinsdorf.

Her debut as Carmen was a success and, in time, she was heard as Amneris (Aida), Marina (Boris Godunov), Ulrica (Un ballo in maschera), the Nurse in Die Frau ohne Schatten and the Old Prioress in Dialogues of the Carmelites.

"[This quote needs a citation] But with Klytemnestra, Resnik met her greatest challenge – "a dramatic conception that is unforgettable and a vocal prowess without limit.

"[This quote needs a citation] Surely among the happiest memories are three comic masterpieces – her Orlovsky in Die Fledermaus, the Marquise in La fille du régiment (with Joan Sutherland and Luciano Pavarotti) and her Mistress Quickly in the Bernstein–Zeffirelli Falstaff of 1964.

[citation needed] Fluent singing in six languages, Resnik crossed stylistic lines from the classic to the romantic, the Wagnerian to the modern.

As the years passed, Resnik developed a steady network of international performances: La Scala, La Fenice, the Paris Opéra (hailed as Carmen), Salzburg, Naples, Vienna, Lisbon, Madrid, Buenos Aires, Munich, Berlin, Brussels, Marseilles, Stuttgart, Hamburg, Chicago, Edinburgh, Santiago and a return to Bayreuth.

She was Master Teacher-in-Residence in the Opera Department of the Mannes College of Music, and was responsible for the preparation of La bohème, The Magic Flute, Don Giovanni, Il tabarro, Gianni Schicchi, The Marriage of Figaro and The Dialalogue of the Carmelites.