The ecclesia or ekklesia (Greek: ) was the principal assembly of the democracy of ancient Athens. It was the popular assembly, open to all male citizens as soon as they qualified for citizenship. In 594 BC, Solon allowed all Athenian citizens to participate, regardless of class, even the thetes. The assembly was responsible for declaring war, military strategy and electing the strategoi and other officials. It was responsible for nominating and electing magistrates (árchontes), thus indirectly electing the members of the Areopagus. It had the final say on legislation and the right to call magistrates to account after their year of office. A typical meeting of the Assembly probably contained around 6000 people, out of a total citizen population of 30,000-60,000. It would have been difficult, however, for non-wealthy people outside the urban center of Athens to attend until payments for attendance were introduced in the 390s. It originally met once every month, but later met three or four times per month. The agenda for the ekklesia was established by the Boule, the popular council. Votes were taken by a show of hands, counting of stones and voting using broken pottery.
In ancient Greece an ekklesiasterion was a building specifically built for the purpose of holding the supreme meetings of the ecclesia. Like many other cities Athens did not have an ekklesiasterion. Instead, the regular meetings of the assembly were held on the Pnyx and two annual meetings took place in the Theater of Dionysus. Around 300 BC the meetings of the ekklesia were moved to the theater. The meetings of the assembly could attract large audiences: 6,000 citizens might have attended in Athens during the fifth century BC.
A police force of 300 Scythian slaves carried red ochre-stained ropes to induce the citizens who loitered in the agora of Athens to attend the meetings of the assembly. Anyone with red-stained clothes who was not in the meeting was liable to a penalty.