In 1937, Roger Wagner joined the MGM chorus in Hollywood and was subsequently appointed Music Director of St. Joseph's Church in Los Angeles where he established an outstanding choir of men and boys, including a young Paul Salamunovich. In 1945, Roger Wagner became the supervisor of young choruses for the City of Los Angeles, most notably the "Los Angeles Concert Youth Chorus." It was from a madrigal group of twelve of these singers that the Roger Wagner Chorale was born in 1946.

The Roger Wagner Chorale became recognized the world over through its numerous radio, concert, and television appearances, motion picture soundtracks The Gallant Hours, and more than eighty recordings (they were also famous for singing the theme song and "score" for I Married Joan). The Virtuoso recording won a Grammy Award in 1959, and the popular carol recording Joy to the World was a Gold Record Album, selling more than a half million copies. The Chorale toured all over the world and included such outstanding singers as Marilyn Horne, Marni Nixon, Claudine Carlson, Harve Presnell (on several recordings), Salli Terri (on several recordings as well as researching for several of the LP liner notes), Earl Wrightson and Carol Neblett.

In 1964, on completion of the Los Angeles Music Center, Wagner and representatives of the Junior Chamber of Commerce formed a resident choral ensemble, the Los Angeles Master Chorale, which became a resident company of the Music Center alongside the Los Angeles Philharmonic. Credits include performance with Eugene Ormandy and the Philadelphia Orchestra in the Presidential Inaugural at the Kennedy Center in 1973 and a tour of the Soviet Union as a United States State Department "cultural ambassador" in 1974. Wagner served as the Chorale's Music Director for 22 years until he was named Music Director Laureate.

The Chorale's 1951 recording of Giovanni Pierluigi da Palestrina's "Pope Marcellus Mass" was selected by the Library of Congress as a 2010 addition to the National Recording Registry, which selects recordings annually that are "culturally, historically, or aesthetically significant".