This led to his appointment in 1967 as Music Director of the Handel and Haydn Society of Boston, a post he held until 1986. During his tenure there, he transformed the organization from a traditional amateur oratorio society to a fully professional ensemble with a repertoire that ranged from early music to modern works. Michael Steinberg described his work: "His performances are clean, transparent, rhythmic and, in a broad repertory from Schütz to Dallapiccola and Stravinsky, he is particularly effective in works with chorus." The "New York Times" said that his work "helped animate the early music revival that took place in the mid-20th century and afterward". His ensembles used modern instruments but comprised fewer players; the ensembles' "clean, spare sound harked back to 17th- and 18th-century models".