This chapter examines the use of ADR - and more particularly arbitration mechanisms - available to Muslims in the UK and in Singapore. With the rising importance of arbitration and other methods of ADR across many areas of law, the use of 'religious arbitration' has come to the fore. One of heralded virtues of arbitration has been its capacity to allow parties to choose the law governing their agreements and to choose the arbitrators to settle disagreements. In this respect, arbitration, even more so than other ADR methodologies, may be viewed as 'pluralism enhancing' since it opens the possibility of a wide range of different legal orders operating within one jurisdiction. When arbitration meets religious norms, however, certain issues can arise. First, need there be any limitation on the impact of religious norms in the arbitration process at either the level of substantive law or background of the arbitrators? Second, what if the substantive law that comes from religious norms is itself subject to diverse interpretations? The second issue is particularly relevant where the invocation of the Shari'a in arbitration agreements can actually invoke a broad spectrum of legal opinion. If states attempt to define the Shari'a, they may bring clarity to these norms. However, such a process runs the serious risk of constricting the interpretive plurality inherent in the Shari'a, and thus could, paradoxically, undermine the pluralism enhancing virtues of arbitration. The chapter will explore these issues by examining the different contexts of the UK and Singapore.