Athanasius was one of the first writers to argue for the Holy Spirit's divinity, and the majority of his seven dozen works include at least one reference to the Holy Spirit. Yet, Athanasius is mainly remembered for his Christological writings and role in the so-called "Arian" controversy. Only a limited number of studies have looked at his pneumatology, and these studies have usually focused on Athanasius’s Letters to Serapion on the Holy Spirit (ca. 359–361), leaving a gap in our understanding of Athanasius’s prior pneumatology. By exploring the period from Athanasius’s election as bishop (328) to the completion of the third Oration against the Arians (ca. 345), this book seeks to help fill this gap. The first part argues that by the mid-330s, Athanasius had begun to establish core pneumatological perspectives that he would maintain for the rest of his career. Part two examines Athanasius’s three Orations, giving particular attention to Orations 1–2. Without the pneumatological perspectives that he established in the 330s and 340s, Athanasius would not have been prepared for his Letters to Serapion, where he took the next steps of confessing the Holy Spirit’s divine nature and role in creating the world.