Voltaire's role in the luxury debate, the controversy about civilisation, capitalism, and progress which accompanied the birth of modern consumer society in the eighteenth century, is generally limited to his Mondain and its Défense, and reduced to a hedonist apology for luxury. The thesis sets out to re-examine and refute this. It analyses Voltaire's discovery of commercial societies in Holland and England, and, focussing on the latter, it finds that the apology for commerce became a centralising theme in the Lettres philosophiques, explaining its purpose and coherence. The thesis then turns to Voltaire's apology for luxury in the 1730s, analysing how du Châtelet and Voltaire, having recourse to classic Epicureanism and deist voluntarism, transformed Mandeville's Fable of the Bees into a justification of commercial societies. Close readings of the Mondain and its companion pieces provide further proof that Voltaire's position on luxury was more nuanced than previously assumed. The Siècle de Louis XIV and the Essai sur les moeurs demonstrate the importance of luxury in Voltaire's view of civilisation, which in turn serves to explain the shift in Voltaire's appreciation of Montesquieu. The thesis opposes the claim that in later life Voltaire adopted a Rousseauian view of luxury. Examining Voltaire's later poetry on luxury in light of the analyses offered in the previous chapters, it concludes that his position remained consistent and showed no Rousseauian influence. Concluding with Voltaire's last defence of luxury, his entries 'Luxe' in the Dictionnaire philosophique and the Questions sur l'Encyclopédie, the thesis explains, with the help of the Fragments sur l'Inde, why and how his attitude to luxury seemed ambiguous in the latter work. The thesis thus proves that Voltaire's contribution to the debate was not only sustained, independent, and carefully nuanced, but that the debate itself played a crucial rule in Voltaire's thought and writing.