This article evaluates Andreas Wimmer's theory of ethnic boundary making by applying it to the maintenance of Jewish ethnic identification in Sweden, as expressed in interviews with Swedish Jews. Wimmer proposes that ethnic conflict routinizes and entrenches perceptions of ethnic difference; we argue that the antisemitic persecutions of the twentieth century have entrenched the perception of the ethnic distinctiveness of Jews among Jews themselves. These persecutions also contribute to alienation from Swedish society, which does not share the same frames of understanding. These factors motivate the interviewees to maintain the ethnic boundary between Swedes and Jews and guard it against assimilation. We propose a nuancing of the debate between instrumentalist and primordialist conceptions of ethnic identity by arguing that while our interviewees express a taken-for-granted view of their ethnic identities, they advance ethnic discourse strategically in order to protect the Jewish community from losing its distinctness, especially through assimilation.