Solon's reforms were not in the long term successful in resolving the differences and reconciling the interests of the various social groups. In 560 B.C. the Athenian families were divided into three sides corresponding to place of origin: the Pediaei, the Paralii and the Diacrii, their chiefs being respectively Lycurgus the Eteobutad, Megacles the Alcmaeonid, and Pisistratus. The last-named, as polemarch, was leader in the Megarean War. But by accusing his political opponents of attacks, he managed to obtain permission to form a body of three hundred men carrying clubs, with whose help he seized the Acropolis. His first period of tyranny lasted six years. But he regained power eleven years later with Alcmaeonid support. Having collected contributions from Eretria, Thebes and the Pangaeum region, he formed a body of mercenaries, landed at Marathon in about 546 B.C., and defeated his enemies at the battle of Pallene.

According to Aristotle, he followed a moderate policy. He sent his political opponents, who included Alcmaeonids, into provisional exile, but did not confiscate their property. He perhaps went so far as to make a redistribution of the land; at all events it is sure that he made interest-free loans available to small cultivators. Moreover, he consolidated the deme lawcourts, in order to make things easier for the inhabitants of the countryside and to curtail the power of the eupatrids; or, according to Aristotle, because the concentration of citizens in Athens might have been a threat to his power.

He minted the first Athenian coinage, and supported the development of trade and handicrafts. His skill in diplomacy was evident from his success in winning control of the Chersonese at the Hellespont, which controlled the road to what was a lifeline for Athens, the grain-producing regions of Scythia. At the same time, on the symbolic level, his introduction of the cult of Dionysus, his rebuilding of the Parthenon and the brilliance of the festival of the Great Panathenaea all made for the identification of the inhabitants of the countryside with the Athenian citizen body, and for the lessening of the importance of local cults, which were under the supervision of the aristocratic families.

When Pisistratus died he was succeeded by his two sons, Hippias and Hipparchus, who was assassinated in 514 B.C. by Harmodius and Aristogiton. This assassination, the motives for which are still debatable, did not immediately result in the overthrow of the tyranny, which was achieved with the intervention of Sparta. In 510 B.C. Cleomenes king of Sparta attacked Athens, at the invitation of the Alcmaeonids, and expelled Hippias.