In 1581, Pope Gregory XIII in his bull Antiqua iudaeorum improbitas authorized and expanded inquisitorial jurisdiction to include professing Jews (those Jews who openly practised Judaism). This chapter begins by listing the extant sources available regarding this inquisitorial jurisdiction in various inquisitorial archives in Italy. Then, using hitherto unused processi in the Modenese archives, it questions the level of disruption caused by the inquisition to Jewish life in the ducal capital and the lives of individual Jewish families in the outer peripheral towns of the Duchy. Through the lens of a centre/peripheral perspective, it then questions how far the Modenese tribunal used its own initiative and judgement in disciplining Jews rather than following orders from Rome. It concludes with an attempt to define the somewhat artificial absorption of Jews into inquisitorial jurisdiction.