performed with frequency during these years was J.S. Bach's Mass in B Minor, which he first performed in February 1955 with the Chicago Symphony Orchestra under conductor Margaret Hillis. He later performed the work with the Boston Symphony Orchestra at Tanglewood in the summer of 1955 and with the Philadelphia Orchestra at the Bethlehem Bach Festival in 1956. In March 1955 he sang Helenus in a lauded production of Berlioz's Les Troyens with the New England Opera Theater opposite Eunice Alberts as Cassandre, Marriquita Moll as Dido, and Arthur Schoep as Aeneas. The year 1958 proved to be a banner year for McCollum. In April of that year he was the tenor soloist in Haydn's The Creation with sopranos Adele Addison and Louise Natale, baritone Mack Harrell, the New York Philharmonic, and conductor Robert Shaw. Later that month he sang Ferrando in Mozart's Così fan tutte with the Washington Opera Society in Washington, D.C. The following June he made his European debut at the very first Festival dei Due Mondi as Reuel in the world premiere of Lee Hoiby's chamber opera The Scarf with Patricia Neway and Richard Cross. In August he performed the title role in Gioacchino Rossini's Le comte Ory at Tanglewood and in October he performed in Thomas Arne's rarely heard opera Comus with The Little Orchestra Society. In 1959 McCollum performed Handel's Ode for St. Cecilia's Day with the New York Philharmonic under conductor Leonard Bernstein. He also returned to Tanglewood to perform with the Boston Symphony Orchestra in Berlioz's Requiem. Later life and career Up to this point in his career, McCollum had mainly been busy performing as a concert singer and had not spent the majority of his time performing in operas. This began to change in early 1960s when he began to perform much more frequently in operas, although his concert career remained active. He performed with companies across North America during the 1960s, including the Opera Company of Boston, the Canadian Opera Company, the Cincinnati Opera, the Seattle Opera, the Washington National Opera, and Vancouver Opera among others. He sang four roles with the Santa Fe Opera during the 1962 summer season: Ferrando, the second tenor in Igor Stravinsky's Renard, The Fisherman in Stravinsky's The Nightingale, and Alfredo in La traviata. He remained active with the Boston Symphony Orchestra during the 1960s, performing in concerts of Berlioz's La damnation de Faust and