This dissertation is an examination of the pneumatology of Origen of Alexandria. By providing insight into his understanding of the Holy Spirit, it also seeks to reframe the way in which Origen’s Trinitarian theology is understood. In this study, I argue that Origen conceives of the Holy Spirit as a divine person, but inferior in nature. Origen’s pneumatology must be considered in light of his understanding of the Son and Father, as well as the influence of Middle Platonism on his theological and cosmological framework. Origen’s concept of Trinity is a hierarchy of divine persons in which the greater ministers to the existence of the lower. Though Origen recognizes the personhood of the Holy Spirit, he believes that the Spirit is less than the other divine persons, both in person and in work. The Spirit’s origin and attributes, for which Origen has no real scriptural or traditional precedent, he struggles to articulate and often leaves unresolved. I suggest that Origen’s pneumatology can be best understood by examining where he is most clear and consistent: the work of the Holy Spirit. Origen consistently portrays the Spirit as participating in the divine work of salvation; his Trintarianism is strongly economic, emphasizing shared work and will. The Spirit’s specific role in the economy is to indwell and assist the saints, in line with his lesser status. There are two ways in which the Holy Spirit’s activity can be framed: (1) in the Trinitarian and downward action of God, in which the Spirit is the direct distributor of the divine gifts and graces and (2) the Spirit’s upward work of revelation and sanctification, by which he leads the saints to the Son and Father. The Spirit thus serves as the practical and personal initiator of believers into the greater processes of salvation and deification.