This chapter investigates the relationship that existed between the Houses of the Catechumens and the central and local offices of the inquisition, through the analysis of a specific case: the Este Duchy, in northern Italy. The Houses of the Catechumens were places of isolation, where Jews waiting to be baptized and become Catholics were accommodated. The abundant documentation conserved in the archives reveals a lack of interaction with the inquisition, at both central and peripheral level. In addition, the politic of conversion that inspired the Church in the modern age did not seem to be effectively pursued either by the Houses or local inquisition: converted Jews represent a small percentage, and Jewish communities were not scratched numerically by the activities of the institutions dedicated to their conversion (Inquisition, Houses of Catechumens and ghettos). The focus of Catholic authorities turned rather to limit the sociability between Jews and Christians and often used the fines imposed on Jews as a form of self-financing for the Houses and the local inquisitions, always looking for economic resources.