This article explains the development and face validity of the Generalised Antisemitism (GeAs) scale, which provides an up-to-date measure of antisemitism consistent with the International Holocaust Remembrance Alliance Working Definition of Antisemitism (generally known as the IHRA Definition). The GeAs scale is comprised of two six-item subscales, each containing a balance of reverse-coded items: the Judeophobic Antisemitism (JpAs) subscale, which tests for endorsement of “classic” prejudicial attitudes towards Jews, and the Antizionist Antisemitism (AzAs) subscale, which tests for endorsement of related attitudes expressed in relation to Israel and its supporters. Both subscales reflect the current state of historical and social scholarship on antisemitism and have already been employed in large-scale survey research with funding from Campaign Against Antisemitism. Findings of a validation study presented elsewhere are summarized, and the scale’s use in future scholarly and stakeholder research is recommended.