The last several decades have seen both a renewed anthropological interest in the possibility of cross-cultural comparison and the rapid rise of the anthropology of Christianity. These two trends should be mutually supportive. One of the promises of the anthropology of Christianity from the outset has been that it will allow people to compare how processes of Christianization have unfolded in different parts of the world and to consider how the resulting Christian configurations are similar to and different from one another. But to this point, relatively little detailed comparative empirical work on Christianity has appeared. Our aim here is to contribute to remedying this situation. Drawing on recent theoretical work on comparison, we set comparative work on Christianity on a new footing. Empirically, we examine how processes of Evangelical Christianization have transformed notions of the self in one Amazonian society (Wari') and two unrelated societies in Melanesia (Bosavi and Urapmin). We define the self for comparative purposes as composed of ideas of the mind or inner self, the body, and relations between people. In our three cases, Christianization has radically transformed these ideas, emphasizing the inner self and downplaying the importance of the body and of social relations. While our empirical conclusions are not wholly unexpected, the extent to which the details of our three cases speak comparatively to one another, and the extent to which the broad processes of Christian transformation they involve are similar, are surprising and lay a promising foundation for future comparative work in the anthropology of Christianity.