 Marcus taught on the faculty of the Juilliard School in New York City from 1954 to 1990.She also gave master classes in piano performance at other conservatories, including the American Conservatory of Music in Chicago during the 1970s, in collaboration with William Browning, also a teacher of great repute.Marcus's performances included a Carnegie Hall recital on January 25, 1949, in which she played Scarlatti, Brahms, Schubert, Schumann, Scriabin, Rachmaninoff, Stravinsky and Chopin.