He was born in New York City in 1913. He became a talented piano player and composed music for the theater. In the 1940s he began to work in Hollywood, where he would compose music for 16 films from 1948 to 1969.

His best known film score is that for the 1958 movie The Big Country, for which he was nominated for an Academy Award for Original Music Score. According to Moross, he composed the main title after recalling a walk he took in the flat lands around Albuquerque shortly before he moved to Hollywood in the late 1930s.

Among his other works include the music for the films The Adventures of Huckleberry Finn (1960), The Cardinal (1963), and Rachel, Rachel (1968). He also composed the main theme to the 3rd-8th seasons of the TV series Wagon Train and was a composer on many other films.

He also orchestrated for other composers, including such films as Our Town for Aaron Copland and The Best Years of Our Lives for Hugo Friedhofer.

Moross's concert works include a symphony (whose premiere was conducted by Sir Thomas Beecham), a sonata for piano duet and string quartet.

Moross died in Miami in 1983 of congestive heart failure following a stroke.

Work on Broadway

Mother (1935) - play - co-incidental music composer,

Susanna and the Elders (1948) - one-act musical - composer,

Willie the Weeper (1948) - one-act musical - composer,

The Eccentricities of Davey Crockett (1948) - one-act musical - composer,

The Golden Apple (1954) - musical - composer