[5] He studied with the American Theatre Wing[5] from 1949 to 1951 and began his career as an actor, making his Broadway debut in The Prescott Proposals in 1953.
Following a national tour, Masteroff's first play, The Warm Peninsula, opened on Broadway at the Hayes Theater in January 1959 with Julie Harris, June Havoc, Farley Granger, and Larry Hagman in the lead roles.
[7] Three years later, when Hal Prince gained control of the rights to John Van Druten's play I Am a Camera and The Berlin Stories by Christopher Isherwood, he discarded the book for a musical adaptation already written by Sandy Wilson and hired Masteroff to fashion his own.
[9] Masteroff's next and final Broadway project, 70, Girls, 70 was less successful, closing one month after it opened in April 1971.
He wrote the book and lyrics for the musicals Six Wives (Off-Broadway, 1992)[11] and Paramour, the latter based on Jean Anouilh's The Waltz of the Toreadors (Old Globe Theater, San Diego, 1998).