This chapter explores distinctive features of Lucretius’s presentation of Epicureanism, particularly his use of verse and the interplay between the poem’s overt concern with physics and its underlying ethical message. The De rerum natura—it is argued—seeks constantly to bring out the ethical corollaries of Epicurus’s physical theory (emphasizing, for example, the harmful consequences of belief in vengeful deities; the self-destructive behaviours, on both the individual and the social level, that stem ultimately from the fear of death; and the futility of uncontrolled desire). While adhering closely to the writings of Epicurus himself, and showing little interest either in subsequent developments within the school or in contemporary inter-school polemics, the poem does, arguably, seek in various ways to adapt the arguments of the founder to the purview of its Late Republican audience. The chapter briefly considers the extent to which Lucretius adapted, or redeployed, arguments originally directed at Platonic/Academic targets as weapons against contemporary Stoicism, and notes other areas—particularly religion and human-animal relationships—where the poet can be seen to give his own distinctive slant to Epicurus’s teachings. Lucretius’s justification for his highly unorthodox use of poetic form is examined in detail, and the chapter concludes with the suggestion that the De rerum natura self-consciously pits Epicureanism against Roman aristocratic ideology, both through its highly original analysis of contemporary political competition and social breakdown, and—more subtly—through its employment of “social metaphor” and depiction of atomic interaction as a microcosm of human society.