This book charts the history and influence of the most vitriolic and successful anti-Semitic polemic ever to have been printed in the early modern Hispanic world and offers the first critical edition and translation of the text into English. First printed in Madrid in 1674, the Centinela contra judíos (“Sentinel against the Jews”) was the work of the Franciscan Francisco de Torrejoncillo, who wrote it to defend the mission of the Spanish Inquisition, to call for the expansion of discriminatory racial statutes and, finally, to advocate in favour of the expulsion of all the descendants of converted Jews from Spain and its empire. Francisco de Torrejoncillo combined the existing racial, theological, social and economic strands within Spanish anti-Semitism to demonize the Jews and their converted descendants in Spain in a manner designed to provoke strong emotional responses from its readership.