One of the key challenges facing Europe since the end of the Second World War has been to confirm and protect the rights of minority religious groups: Jews in particular, but also Catholics or Protestants (in countries where one or the other group is a minority) and members of other religions who have immigrated into the European Union: Muslims, Buddhists, Hindus, Sikhs and others. The freedom to practice one's religion is a fundamental right inscribed in the laws of the Union and of its member states. Yet in practice, religious expression is perceived differently in various member states and by the members of the diverse religious communities that cohabit in those states. The wearing of a Sikh Turban, a Catholic Holy Week procession, or the call of a muezzin issuing forth from a loudspeaker atop a minaret: each such public expression of religion poses a series of questions involving distinctions between public and private spheres, between religious and cultural symbols, between the identities of religious communities and national polities. The situation is complicated by two contrasting but not mutually exclusive phenomena: an increasing secularization of European societies and a reaffirmation of religious identities. While the broad principles of religious freedom are universally acknowledged, the contours of that freedom in the daily lives of Eu-ropeans of all religions (or without religion) vary from one member state to another and are frequently subjects of debate and polemics. The issues of religious diversity and of the regulation of pluralistic European societies are not new. On the contrary, religious diversity in Europe is grounded in the practice of Christian and Muslim states of the European Middle Ages. In the Christian Roman Empire of the fifth and sixth centuries, emperors banned paganism yet allowed Jews limited freedoms, creating a protected but subordinate status for the empire's Jewish subjects. In the wake of the Muslim conquests of much of the former Roman/Byzantine Empire, Muslim rulers accorded to Jews and Christians the status of dhimmīs 1 , protected minorities that enjoyed broad religious freedoms and judicial autonomy, but whose social and political status was inferior to that of Muslims. In Christian kingdoms of medieval Europe, Jews (and in some cases Muslims) were accepted as subordinate minorities who could maintain their synagogues and mosques and openly practice their religions. Towards the end of the Middle Ages, the status of these religious minorities became increasingly precarious in many European states: minorities faced violence and often expulsion: this is the case for Christians and Jews in Almohad Spain (twelfth and thirteenth centuries), for Jews in many medieval and early modern states, and for Muslims in Sicily (thirteenth century) and Spain (fifteenth and sixteenth centuries).