Initially, Montenegro was the staff manager to André Kostelanetz at Columbia Records in New York, which eventually led to a job as a conductor/arranger for several of the label's artists, most notably Harry Belafonte. By the mid-'50s, Montenegro was making his own albums of easy listening orchestral music.
Montenegro moved to California in the mid-'60s and began to write film scores, starting with Otto Preminger's Hurry Sundown in 1967. That same year, he recorded a version of the theme to The Good, the Bad and the Ugly, which was written by Ennio Morricone. Featuring an arrangement that relied on a chorus, electric instruments, and special effects, the single was a major hit, reaching number one in the U.K. and number two in the U.S.; internationally, it sold over a million copies. An album titled Music from The Good, the Bad and the Ugly A Fistful of Dollars For a Few Dollars More appeared shortly after the single's release, and it reached the Top Ten in the spring 1968. Later in the year, Montenegro released a single of the theme from Hang 'Em High, which was a lesser hit, as was the album of the same name.
Montenegro began to branch out after the Hang 'Em High album, recording a diverse array of albums, ranging from show tunes to electronic experiments. Throughout the late '60s and '70s, he continued to score films, including #Lady in Cement, #The Undefeated, #The Wrecking Crew, #Tomorrow, and #The Ambushers, among many others. He continued composing and recording until his death in 1981. ~ Stephen Thomas Erlewine, Rovi