Non-denominationalism, the credo of the 19th century Congregationalist colleges established in the Ottoman Empire, is a little understood concept particularly when interpreted within a generic paradigm of conversion into Christianity or only against the background of the Ottoman religious categorizations regarding non-Muslims. In the absence of historical references to the debates of the time over the denominational nature of college education in New England, most of the extant literature on American missions in the Ottoman Empire reads this concept either as an early precursor of secularism or a belated sign of ecumenical Christian brotherhood. Pursuing another track, this paper explores the mechanisms through which the crystallization of the denominational identities in New England in the 19th century informed the debates surrounding the establishment of American colleges in the Ottoman Empire and the self-presentation of these institutions to the local populations as ‘non-denominational’. The paper first focuses on the internal debates of ABCFM, the American missionary institution which facilitated the global spread of a particularistic Congregationalist view on the relationship between education and religion in cooperation with the Presbyterians. And then, it examines to what degree the missionaries stationed in the Ottoman Empire thought Bostonian views regarding denominationalism resonated with the problems they encountered in the field particularly when deployed within the context of the millet system. The wounds of the trauma surrounding the carving out of the Unitarian colleges out of the Congregationalist collegial map of Massachusetts, which was exacerbated by the subsequent struggle between the Presbyterians and Congregationalists over the control of the religious and educational field of New England are traced in the personal papers of both the missionaries who were involved in the debate in Boston and in charge of the foreign missions, and the missionaries who were instrumental in establishing American colleges in Constantinople and Beirut. The central argument derived from this contrapuntal reading of archival sources from both sides of the Atlantic is that the institutional stories of the colleges in the Middle East cannot be adequately written unless we engage in an analysis of the involved actors’ actions in a manner that articulates the various cultural spaces they inhabited simultaneously although they may be oceans apart: their referential cultural spaces, their local, everyday cultural landscapes and the global field within which these geographically and culturally separate spheres relate to one another.