This chapter focuses on Cicero’s treatment of the emotions in Books 3 and 4, and more specifically on his account of the dispute between the Stoics and the Peripatetics. At first sight, the dispute seems uncomplicated: the Stoics advocate the complete absence of emotions whereas the Peripatetics hold that emotions should rather be moderated or controlled. But Cicero’s stress on the idea that emotions are beliefs seems to come at the expense of other central parts of the theory of emotions, most prominently the theory of action.  I argue that these features of his presentation serve him in securing a thesis that he is keen to defend in Book 5: that virtue guarantees happiness and that this happiness is invulnerable to the accidents of fortune.