The dissertation examines the social reality of the second-and perhaps most decisive-wave of religious conversion to Islam. Eschewing earlier approaches that focused on the plight of the disempowered (and which were entirely based on Muslim sources), I try to restore some agency to the Coptic community and nuance the traditional picture of religious conversion as either directly forced or opportunistically sought. By relying on unpublished Coptic sources, I also bring in the tenuous and often delicate relationship between the Coptic Church and the congregation and the way in which the dynamics (and availability) of conversion affected this relationship. I also rely on documentary source from which we can glean a less mediated picture of social practice and kinds of ruses and subterfuges that narrative sources are less likely to reveal. Finally, I address the effects of the conversion wave on Islam-not only in the new Muslims' (the converts') importation of beliefs and practices into the new community, but also in the destabilising effects mass conversion had on identity and identification, a development that provoked a new denunciatory literature from conservative Islam and which, in elaborating 'heretical innovations' reconstituted orthodoxy, and more generally, Islam.