The Stoic School was started in the final decade of the fourth century before the Christian era, by a certain Zeno: not the earlier Eleatic paradox-monger, but a native of the Cypriot city of Citium, and thus usually distinguished as ‘Zeno of Citium’. His date of birth is unknown – probably around the 330s bce – but his death can be dated with fair confidence to 262 bce, when the school that he had founded came under the leadership of his student and successor, Cleanthes of Assos. Cleanthes was succeeded thirty years later by the greatest of the Stoic line, Chrysippus of Soli.

Although none of these three were Athenians by birth, they all studied and worked in Athens, and were deeply influenced by the schools of Athens that preceded them: Plato's Academy, first and foremost, but Aristotle's Lyceum as well, and even, in an adversarial way, the roughly contemporary and rival school of Epicurus. They also absorbed the writings of Xenophon, who had been a student of Socrates alongside Plato and wrote his own Socratic dialogues, although he left no school behind. Many facets of Stoic theory show the influence of the Socratic legacy – their theology as much as their ethics – and the Socrates that they imitated was just as often Xenophon's as Plato's.

Stoicism had intelligent and interesting proponents to its name for the next four hundred years; the school made an easy passage to Rome when Rome eclipsed Greece in the second century bce, and it even found adherents among the early Christians.