This dissertation reappraises the treatment of Jews and Muslims under Christian rule in eleventh- and twelfth-century Iberia as it is reflected in fueros and cartas de población. The proliferation of these charters coincided with the expansion of the Christian realms of northern Iberia, both in competition with each other and with the Andalusī states. The dissertation traces the mentions of non-Christians in the fueros from their first appearance in Laws of León (1017), until the proliferation of the fueros extensos, mainly the laws of Estella (c. 1164), Teruel (c. 1178), and Cuenca (c. 1189). This thesis proposes to study the law-making process, examining individual clauses and fueros in their specific political, social, and cultural conditions, in order to fully grasp the edicts regarding non-Christians found in these texts. The dissertation identifies four themes through which fueros addressed these communities. First, assurances of personal protections to non-Christians through the enforcement of wrongdoing procedures and penalties are common throughout the legislation. Second, the fueros granted institutional autonomy to certain Jewish and Muslim groups in different areas of Iberia based on local circumstances. Third, the legislation identified the courthouse as the key arena of conflict in the negotiation of local interaction between Jews, Muslims and Christians. Finally, the fueros distinguished between the treatment of free and unfree Muslims, constituting a major point of contrast between the status of these groups and that of Jews in such legislation. Using these themes, the different chapters of the dissertation explore the diachronic evolution of these clauses in parallel with the changing nature of the law, power and institutions in Christian Iberia. The dissertation argues that in these sources, Jews and Muslims appear as active participants, rather than passive onlookers, in the formation of the societies that they inhabited.