This chapter aims to understand what happens when disputants hold and promote quite contradictory arguments about nature and morality, specifically within the context of debates about biotechnology. In D. Nelkin's accounts of controversy, it is the underlying values, politics and morality of developments in science which serve as the principle negotiating territory within which such debates are fought out. The chapter addresses the way in which these debates are varyingly negotiated by two of these key constituencies. First, a number of biotechnology and pharmaceutical firms have invested heavily in the field, particularly in the mid 1990s though somewhat more modestly of late. On the other hand, these developments have been vigorously opposed by a number of animal advocacy Non Governmental Organisations. Both groups have drawn upon a wide range of moral and scientific resources with which to contest or defend the immediate and long-term future of xenotransplantation.