During the 350s, the Emperor Constantius sought to establish ecclesial unity in the West by organizing a number of local synods that demanded the condemnation of Athanasius and support for an anti-Nicene formula of faith. Among the bishops who refused these demands and suffered exile is Hilary of Poitiers. Since scholars have either unnecessarily exaggerated or diminished Hilary's role in the Nicene-'Arian' conflict during this early period and are sharply divided on the reasons for his exile, I will begin with two historical chapters, arguing that Hilary had a limited awareness of the 'Arianism' troubling the West in the early 350s and that he was exiled for his confession of faith at the synod of Béziers. After establishing Hilary's historical situation, I will turn to his chief work and the main focus of this dissertation, his De Trinitate.  De Trinitate begins with what appears to be an autobiographical statement on Hilary's journey to faith. A close reading of this first book, however, reveals a reflection on theological method by Hilary that establishes for the reader the proper way to approach the mystery of God. In this first book, Hilary emphasizes the normative role of Scripture in theological discourse, the proper use of faith and reason in theological inquiry, and the soteriological context of any discussion on the mystery of God.  After two chapters showing how Hilary develops the main features of his theological method throughout his treatise, I address the relationship between Book One and the rest of the treatise. I first offer a close reading of De Fide, books two and three of De Trinitate, showing the continued reflection on the proper approach to the mystery of God. Finally, I turn to Hilary's books against the Arians, books four to twelve of De Trinitate, and address why Hilary combined two works to produce what we now call De Trinitate. A close reading of the text reveals that Hilary's extensive comments on theological method at the beginning of De Trinitate is the main reason he attached De Fide to the books against the Arians.