In the terms of Durheimian sociology, conversion is a fait social. Although they are rarely treated as a cultural phenomenon, conversions can obviously be examined for the norms, values and presuppositions of the cultures in which they take place. Thus conversion can help us to shed light on a particular culture. At the same time, the term evokes a dramatic appeal that suggests a kind of suddenness, although in most cases conversion implies a more gradual process of establishing and defining a new - religious - identity. From 21-24 May 2003, the University of Groningen hosted an international conference on 'Cultures of Conversion'. The contributions have been edited in two volumes, which pay special attention to the modes of language and idiom in conversion literature, the meaning and sense of religious-ideological discourse, the variety of rhetorical tropes, and the effects of the conversion narrative with allusions to religious or political conventions and idealizations. The present volume contains theoretical contributions on the theory of conversion, with special attention to the rational choice theory, and on the history of research into conversion. It also offers stimulating case studies, ranging from the late Middle Ages to present times and taken from Germany, Great Britain and The Netherlands. The other volume, Cultures of Conversion, offers in-depth studies of conversion that are mainly taken from the history of India, Islam and Judaism, ranging from the Byzantine period to the new Muslimas of the West.