I make three basic claims in this dissertation with respect to Lucilian code-switching. First, that the Greek terms used by the poet are reflective of the rich, multicultural literary tradition and social realities present in Rome in the late second-century BCE. Second, that the code-switching devices used by the satirist create tiers of comprehension among his audience, insider and outsider groups that are frequently subverted in accordance with methods typical of and complementary to satire as a genre. And third, that Lucilius, in borrowing words both erudite and mundane, establishes himself as a bilingual philologist of sorts, and makes the motif of language(s) intrinsic to his novel form of satire. I develop my dissertation in four chapters and, for every code-switch analyzed, I examine the relevant Greek and Latin lexical histories in order to determine the types of words borrowed by Lucilius, as well as the possible genres, literary traditions, and contemporary world activated by them. Chapter 1 focuses on the code-switches of the Satires that are semantically philosophical, while Chapter 2 studies those fragments that incorporate code-switches derived from the Homeric corpus (both single words and lengthier quotations). In Chapter 3, the rhetorical code-switches that evoke academic or grammatical contexts and traditions are evaluated. Finally, Chapter 4 centers upon code-switches that I label as “mundane,” a somewhat miscellaneous selection of words from everyday life that can otherwise be characterized as distinctly non-literary. There are sixty-two Greek words and expressions fully examined in these chapters, each a code-switch unique in form and mechanism, all variously contributing to Lucilius’ satiric purpose. The code-switches that I study here thus not only provide a thematic access point for a close, crosslinguistic, and literary analysis of the fragmentary Satires, they also have the potential to reshape how we conceive of the satirist, his genre, his literary legacy, and the intellectual milieu of the second century BCE.