This article considers the different components of the “acquis communautaire” in the matter of religion. The “acquis communautaire” is the set of values, principles and rights that a state has to accept before becoming a member of the EU. EU legal provisions, European Court of Justice (ECJ) decisions and European Court of Human Rights (ECHR) rules are part of this “acquis”, together with the constitutional traditions of the member states. The chapter dwells on this last component, arguing that there is a European model of state-religions relations that is reflected in the constitutional traditions of the EU member states. Whether this “acquis communautaire” is able to face the challenges raised by the growing religious diversity in the EU is discussed in the last part of the chapter.