© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. The etymological study of Early Irish began in the Old Irish period (c. 700‒900 a.d.), under the influence of Isidore of Seville’s Etymologiae, and, because of its flexible hermeneutic potential, it enjoyed great popularity in the middle and early modern periods. It is only with the rise of modern comparative linguistics, especially of Indo-European linguistics in the second half of the 19th century, that the art of Irish etymology attained scholarly rigour. Over the past 150 years, paradigm shifts in Indo-European studies (laryngeal theory, accent/ablaut classes of inflection, derivational morphology) and the development of modern technology (digitisation of texts, e.g. eDIL, ISOS) have repeatedly chang-ed the methods and the course of Irish etymological studies. The impact of some of these external factors will be illustrated with examples.