Spirit Christology has emerged as an important focus in recent theology. It offers new perspectives on christology and pneumatology. Can these new perspectives lead to advances in trinitarian theology itself? The classical theologies o f both East and West tended to express great reserve about moving too easily from the economy o f salvation to ideas about God in se. In the 20th century, Karl Rahner’s axiom that the “economic” Trinity is the “immanent” Trinity and vice versa helped lead to a significant erosion of this reserve, though not without controversy. Coffey (bom 1934) contributes significantly to reflection on this nexus of questions. He explores the relation of Spirit Christology to Logos Christology, arguing that the former need not supplant the latter. He reformulates Rahner’s axiom, suggesting ways of overcoming some o f its ambiguities. He shows that Spirit Christology offers an “ascending” basis for a “mutual love” pneumatology, in the service of a renewed trinitarian theology. This dissertation presents an analysis of Coffey’s achievement in its various contexts, historical and contemporary. It highlights his methodological balance. It argues that his theology represents an important development within the tradition, casting new light on issues of pressing contemporary interest.