He accepted the offer and soon found himself in technique classes with Balanchine, Pierre Vladimiroff, and Anatole Oboukoff, undergoing the strict discipline of the Russian school of classical ballet.

[2] Moncion's first engagement as a professional dancer was as a "gypsy" in a Broadway revival of The Merry Widow, Franz Lehár's famous operetta, with dances choreographed by Balanchine.

When this show closed, in May 1944, he joined the marquis de Cuevas's Ballet International as a principal, creating the title roles in two major productions later that year: Edward Caton's Sebastian and Léonide Massine's Mad Tristan, a Surrealist work with spectacular designs by Salvador Dalí.

[3] Following this engagement, Moncion performed briefly with Colonel de Basil's Original Ballet Russe during the early months of the 1946/47 season.

He was a dashing figure in the Balanchine dances for the Broadway production of The Chocolate Soldier (1947), swirling and twirling with Mary Ellen Moylan.

He was a delicately tender partner to Tanaquil Le Clercq in Jerome Robbins's meditative Afternoon of a Faun (1953), bringing a sensual, feline languor to the part.

He was dramatically powerful in the title role of Balanchine's Prodigal Son, entranced by the Siren of Yvonne Mounsey and then heartbreakingly contrite as he painfully made his way home to his father.

[citation needed] After his retirement from the stage in 1983, Moncion spent his leisure years at his home in Woodstock, New York, indulging his considerable talent for oil painting.