This course explores the forced mass conversions of tens of thousands of Jews and Muslims to Christianity in late medieval and early modern Spain. These forced conversions had enormous impacts on the lives of converts and their descendants, and on the history of Spain and Europe more broadly. We will explore how attacks against Jews and their subsequent conversion led to suspicion of these so-called “New Christians,” resulting in the Spanish Inquisition and the expulsion of Jews from Spain in 1492. We will then delve into the forced conversions of Muslims to Christianity at the beginning of the sixteenth century. Like Jewish converts before them, the descendants of the new converts from Islam were subjected to inquisitorial scrutiny, repression, and eventual expulsion. We will analyze the debates about the place of these converts in Christian society, the politics of identity and assimilation, and the ultimate expulsion from Spain and subsequent dispersion of their descendants.