She remained with O'Neill since 1929 for the rest of his life, and dedicated herself to maintaining his privacy. After his death in 1953, Carlotta authorized the publication of his autobiographical play "Long Day's Journey Into Night", which O'Neill had instructed his publisher to withhold until 25 years after his death. The play was awarded the 1957 Pulitzer Prize for Drama, and is O'Neill's best known work.