Diodorus Siculus’ Bibliotheke has traditionally been seen as a quarry for the lost historians on whose works he drew while researching it. Consequently, Diodorus has not been studied as a historian in his own right, and the Bibliotheke has become little more than a jigsaw puzzle, with sections attributed to any number of lost historians. This dissertation seeks to relocate Diodorus and the Bibliotheke within the Greek historiographical tradition. Therefore it will examine four aspects relating to Diodorus and the Bibliotheke. First, the General Proem will be examined in order to show how Diodorus informed his readers about his aims and methods. Secondly, it will be argued that the General Proem is not an unintelligent repetition of older ideas, specifically those expounded by Polybius in the Introduction to his Histories. Rather, Diodorus builds on the work of Polybius, but more importantly he also interweaves his own original ideas about historiography, particularly universal history. This allows an attempt to elucidate Diodorus’ own contribution to the version of the past narrated in the Bibliotheke. A third section will argue that the events of his own day and the relative position of Sicily within that world heavily influenced Diodorus as a historian, and that to understand Diodorus’ selection and presentation of events in the Bibliotheke note must be taken of these influences. Finally it will be shown, through an examination of Books 18-20, that_Diodorus’ depiction of Rhodes shows that he did not simply follow one source at a time, but often combined several sources when writing sections of the Bibliotheke. We can also see that Diodorus did play a creative role in the representation of events in this section.