[2] Billings began his professional career singing under Sarah Caldwell at the Opera Company of Boston during the company's first season in 1958, singing there regularly through 1970 in such roles as Sellem in The Rake's Progress, Napoleon in the American premiere of War and Peace, and Harlequin in Ariadne auf Naxos.
[8] In 1970 Billings sang in the company of the first national tour of Camelot and returned to the Lyric Opera of Chicago to portray Maestro Spinelloccio in Gianni Schicchi.
[9] He appeared on Broadway in 1971 in the revival of Kurt Weill's Johnny Johnson[10] after which he sang the title role in Don Pasquale with the New York Lyric Opera in Summer of 1972.
[11] The following autumn, he joined the roster at the New York City Opera,[12] making his first appearance in October as Spalanzani in The Tales of Hoffmann, opposite Sills and Norman Treigle.
[13] He continued singing there for roughly the next three decades in well over a hundred roles, including Alcindoro in La boheme,[14] Sacristan in Tosca,[15] Goro in Madama Butterfly,[16] Ko-Ko in The Mikado,[17] Frank in Die Fledermaus,[18] Baron Puck in La Grande-Duchesse de Gérolstein,[19] Henrik Ibsen in Song of Norway,[20] General Novikovich in The Merry Widow,[21] Don Magnifico in La Cenerentola, Badger in Janáček's The Cunning Little Vixen, Beckmesser in Richard Wagner's Die Meistersinger, and Alberich in Wagner's Das Rheingold to name just a few.
[23] In 1989 he portrayed the role of Monsieur Beaunoir in The New Moon which was filmed live for PBS's Great Performances and subsequently released on DVD.