This volume brings together a series of contributions by leading theologians on the doctrine of theosis or deification in the Eastern and Western Christian traditions. While it is still often assumed that the theme of theosis was exclusively developed in the Eastern theological tradition after the Patristic period, and that it has since been a contentious and even divisive theological subject, this volume was explicitly conceived as a forum for ecumenical encounter and as an opportunity to explore articulations of this doctrine in both the Eastern and Western traditions. Presenting case studies that treat a variety of periods, theological fields, and authors, this volume highlights the richness and relevance of the doctrine of deification.