In this thesis I aim to elucidate the philosophical content in Horace's Satires and to assess its implications for our reading. In Chapter 1 I briefly discuss past scholarship on the Satires, with particular reference to the awareness of the philosophical content. I discuss the nature of ancient ethics, arguing that topics involving the practical side of behaviour were seen in a moral context. In this light I compare Horace with Seneca and Lucretius. I discuss Cynicism and the 'diatribe' in the context of what constitutes philosophy, and give an outline of the intellectual scene in 1st Century B.C. Rome. Chapters 2 and 3 concern moderation. I argue for an interpretation in a combination of Epicurean and Aristotelian terms, pointing out the inter relation of ideas through a view of moderation as quantitative/ qualitative - as discussed in modern scholarship on Aristotle. In Chapter 4 I argue that Horace promotes an Epicurean position on Friendship, in opposition to Stoic inflexibility, though he has a unique take on Ambition. In Chapter 5 I show that Horace's discussions of Conduct are examples of ancient ethics in a practical context. Chapter 6 concerns Horace's showcasing and criticism of the Stoic paradoxes - in particular his use of Ciceronian material. In Chapter 7, on literary theory, Philodeman and Aristotelian theory are seen to be important, but, in response to recent scholarship, I find Horace's position deliberately evasive. On Religion (Chapter 8), I argue for an Epicurean position, making comparisons between the Satires and Odes. In Chapter 9 I discuss Horace's use of specific philosophical sources. The philosophical aspects have considerable, sometimes unexpected, implications for our understanding of the Satires. The Satires are not philosophical treatises, but a proper awareness of the philosophical material is important in coming to a rounded interpretation of Horace's work.