Conversion had been an underlying process in the operation of the Roman Inquisition and latently informed and shaped its procedure. This chapter focuses on early modern Venice, which became a hub of religious conversion institutionalized through the Inquisition and the House of Catechumens and, from a comparative perspective, examines cases of Judaizing conversos, Muslims who claimed that they had a Christian background and sought reconciliation with the Church, as well as Protestants or Calvinists from Northern Europe who were converted to Catholicism. The chapter draws on the analytical orientation of “centre and peripheries” to explore this relationship in terms of both geographical/political context and conversion’s place in the overall inquisitorial activity. Conversion has attracted considerable scholarly attention. The chapter seeks to go beyond questions on why and how individuals converted, which have been prominent in current scholarship, to provide a thorough discussion of conversion as a “locus” where various discourses on identity, subjecthood, Self and Other, and religion were articulated and woven together. This chapter argues that the inquisition’s involvement with conversion created durable discourses on identification and classification and established practices that firmly turned individuals into self-identifying Catholics. Conversion cases testified to the increasing collaboration between the local Venetian tribunal and Rome and the shaping of common definitions and norms about the imagery of conversion.