Origen of Alexandria and the Theology of the Holy Spirit offers a comprehensive account of Origen's pneumatology. In examining the Holy Spirit's identity and activity in Origen's writings, this study reads Origen in his context and surveys his entire corpus. It shows that Origen grounds his pneumatology in Scripture and uses Jewish, philosophical, and earlier Christian teachings in exegeting the passages he believes pertain to the Holy Spirit. The Holy Spirit is revealed to function in Origen's works as a single hypostasis dependent on the Father and Son for both his being and attributes, which ranks the Spirit below the Father and Son. The Spirit, however, is grouped with the Father and Son, distinct from all other beings and ranked above them. The Holy Spirit, therefore, is ranked third of all things. This relationship serves as the basis for Origen's belief that the Spirit's activities—giving spiritual gifts, sanctifying believers and making them holy, offering intercession, inspiring Scripture, and aiding in the interpretation of Scripture—are a common operation of the Father, Son, and Holy Spirit. The Spirit, then, plays an integral role in the salvation of the human person. By offering a comprehensive understanding of Origen's pneumatology, Micah M. Miller also provides a fresh perspective of his Trinitarian thought.