In his De re publica and De officiis, Cicero discusses the conditions that must exist for a war to be justly commenced and waged. In developing his account, Cicero lays the groundwork for many of the principles of the later just war tradition. However, commentators have detected inconsistencies between Cicero’s account of ‘the justice of going to war’ and his reliance on the competitive honor code of the ancient Mediterranean world, which undergirds much of his account of conduct within war. Commentators usually see Cicero’s commendation of wars undertaken for the sake of glory as inconsistent both with the legal and religious principles undergirding his account and with the Stoic account of justice derived from Panaetius, whom Cicero follows in De officiis. In this chapter, I reconstruct Cicero’s account of just war theory and explain why he could plausibly see coherence where the modern commentators see incoherence.