No author from antiquity has had more influence on modern perceptions of the ancient poet, Ennius, than the late-Republican orator, Cicero. Indeed, Cicero helped transform the image of Ennius from that of a poet to an auctor, an authoritative source. Likewise, at the hands of Cicero, Ennius’ Annales was portrayed in a variety of ways, ranging from a work with scientific credibility, to a text actively involved in the transmission of Roman culture. This thesis aims to explore the ways in which Cicero constructed the authority of Ennius and his Annales through a close analysis of the citations in his philosophical works. As a result of this examination I hope to shed light on the different authority-building techniques with which Cicero crafted Ennius into a formidable source of auctoritas, while also considering his motives and the consequent image of Ennius that arises.