This chapter explores a variety of philosophical engagements with Cicero in the long eighteenth century, with particular attention to the varied, and at times contradictory, purposes that Cicero might serve. Following an introductory discussion of Cicero and John Locke, the chapter proceeds thematically, turning first to Cicero and eighteenth-century ethics, then to eloquence, civil religion, and law, and finally to Cicero’s status as an exemplar of the active life. In exploring these themes, the chapter deals with the Earl of Shaftesbury Anthony Ashley-Cooper, David Hume, Jean-Jacques Rousseau, Adam Smith, Montesquieu, John Adams, James Wilson, and Immanuel Kant.