Michael Leoni, a leading singer in late eighteenth-century London, became famous for his role in Richard Brinsley Sheridan's anti-Jewish opera The Duenna. He was discovered, however, at the Jewish synagogue, where his singing enthralled non-Jews in the early 1770s. Tracing Leoni's public reception, this article argues that the performative effect of his singing had a multifaceted relation to his audience's psychology of prejudice, serving to both reiterate and reconfigure a variety of preconceptions regarding the Jews. Leoni's intervention through operatic singing was particularly significant––a powerful, bodily manifestation that was capable of transforming listeners while exhibiting the deep acculturation of the singer himself. The ambivalence triggered by his performances would go on to define the public reception of other Jewish singers, particularly that of Leoni's protégé, John Braham, Britain's leading tenor in the early nineteenth century. Ultimately, the experience of these Jews' performances could not be easily deconstructed, as the Jewish performers' voices were emanating from within written, sometimes canonical, musical works. This representational impasse gave rise to a public discourse intent on deciphering their Jewishness, raising questions of interpretation, intention, and confession.