Bernard Lonergan's De constitutione Christi was written to accompany a course being taught in Latin at the Gregorian University, Rome during the 1950s and 60s. This little-known treatise, volume seven in the series, is presented in English translation, accompanied by the original Latin text. Here, Lonergan tackles the metaphysical and psychological questions raised by the unique makeup of Christ, who is both fully human and fully divine, according to traditional Christian theology. His analysis falls into two parts: ontological and psychological. In dealing with the ontology of the incarnate Word, Lonergan explores the notion of person, and in doing so provides an interesting treatment of the existential question of personal authenticity raised by Kierkegaard and treated by Lonergan under the heading of Existez. Moving into his psychological analysis, he argues that consciousness is not a matter of introspection, a perception of oneself as object, but rather an awareness of oneself as subject. He then applies this understanding to the self-awareness of Christ, with particular reference to the question of Christ's knowledge of himself as both human and divine. This book is a foundational text in critical areas of contemporary theology; however, it was never widely circulated and has remained effectively unknown to contemporary scholars. With this translation the work will finally be made accessible.