This chapter presents a historical ethnography examining the creation and revision, by the Synod of Argyll in the western Scottish Highlands, of the Gaelic translation of the Westminster Assembly’s rigorous, doctrinally demanding Shorter Catechism (1647): Foirceadul Aithghearr Cheasnuighe (‘A Short Treatise of Questions’). The translation, designed to consolidate Presbyterian authority across the Gaelic-speaking Highlands through large-scale oral catechesis—and not as a tool in formal education—generated multiple texts in manuscript and print. Of these, only the second edition of the Foirceadul, published in 1659, survives today. Close contextual analysis of the Synod’s minutes suggests both how the text first came to be composed in formal Classical Gaelic, and how subsequent resistance from the laity necessitated vernacular-influenced revisions in the second edition to clarify theologically complex passages: the first steps towards a codified standard Scottish Gaelic.