After presenting a survey of the history of the fratres unitores and some considerations on the printing agenda of the Congregation of Propaganda Fide as regards to Armenian liturgical books in the 17th century, the movements and activities of the two Armenian translators of the Dominican Breviary are retraced. The history of that translation is investigated and information on its costs and the places where it was carried out is given, drawing both on hitherto unpublished sources (such as letters, documents, and papers held in the historical archive of Propaganda Fide and the Liber consiliorum of the Dominican monastery of San Pietro in Galata) and contemporary print resources. A description of the manuscript version of the translation is also given, along with that of its printed version and the first Italian translation of its colophon.