Antisemitism has returned as a major issue across the Western world. But while concern about antisemitism is growing, agreement on what constitutes antisemitism is shrinking. Nowadays, charges of antisemitism are hotly disputed, often accompanied by accusations of bad faith, particularly when they concern criticisms of Israel or anti-Zionism. In this article, co-authored with Adam Hosein and David Schraub, we argue that one reason why antisemitism has become increasingly contested is because there are different ways of thinking about antisemitism and identifying it. We examine four common and contrasting approaches to identifying antisemitism, highlighting the challenges each presents when it comes to identifying antisemitism in practice. Since these alternative approaches yield different answers about whether something is antisemitic or not, disagreement and debate over allegations of antisemitism is unavoidable. Hence, we conclude by offering suggestions for how antisemitism claims should be addressed in a way that minimizes conflict and promotes greater awareness about the various ways that antisemitism can operate. The article is published in the journal Ethnic and Racial Studies (vol. 45, no. 9, pp. 1803-1824):