The relationship between Lowell Mason (1792–1872) and the Boston Handel and Haydn Society (est. 1815) has long been recognized as a crucial development in the history of American music. In 1821, Mason and the HHS contracted to publish a collection of church music that Mason had edited. While living in Savannah, GA, Mason had imported several recent British collections that adapted for church tunes works by Franz Joseph Haydn, Wolfgang Amadeus Mozart, Ludwig van Beethoven, and Ignaz Pleyel. His study with German émigré Frederick L. Abel allowed him to harmonize older tunes in standard counterpoint. In the historiography of American music, the collection has ever since been named as one of the chief forces establishing standard counterpoint in the mainstream of American music. The collection’s profits also helped the HHS survive the next several years, and the prestige of eventually being known as the collection’s editor helped launch Mason’s influential career in church music, music education, and music publishing. In 1827, that career took a dramatic turn when Mason returned to Boston to assume the presidency of the HHS and the care of music in several churches. This project shows that the social ties between Mason and the HHS begin earlier and are far more indebted to Calvinist orthodox Christianity than previous studies have shown. With special attention to Mason’s personal papers housed at Yale University, to the HHS records held at the Boston Public Library, and to newly indexed Savannah newspapers, it shows that Mason’s relationship with the Society grew from relationships begun before he left his native Massachusetts in 1812. The depth of the relationship grew steadily until 1827, marked at first by indirect contact and in 1821 by Mason’s trip to Boston. Mason’s 1827 return to Boston, often surprising to scholars, appears here as a logical consequence of the support given by the Society’s previous president, Amasa Winchester, for Mason’s work in church music. Mason’s departure from the Society seems to be based on his zeal, closely related to his evangelical goals, for universal music education.