In this article, I propose Isidore of Seville’s Etymologiae as a source for three passages in Ælfric’s Preface to Genesis. With these source identifications established, I further develop the argument to claim that Isidorian techniques are a key influence on Ælfric’s assumptions about biblical language, translation, and interpretation as reflected in the Preface. Such assumptions, in fact, inform the vernacular pedagogical project at the heart of the Preface as an introduction to his translation of Genesis into Old English.