This study of controversy over the eucharist in sixteenth-century France argues that Calvinist interpretations of the Lord's Supper played a crucial role in the development of early modern revolutionary politics. Focusing on new understandings of signs and symbols conveyed in Protestant eucharistic writings, Elwood shows how eucharistic doctrine facilitated new conceptions of the nature of power and the relation between society and the sacred and contributed to the development of the divergent religious, social, and political ideals that threatened to destroy France in the second half of the sixteenth century.