One of the most important duties of the Council of Five Hundred was to draft preliminary decrees (provouleumata) for discussion and approval in the Assembly of Citizens (Aristotle, Athenian Constitution 45.4). It also managed state finances and the treasuries of the priests. It was responsible for the arming and manning of the triremes as well as the cavalry, and was in constant contact with the archons (magistrates) and the strategoi (generals) (Aristotle, Athenian Constitution 46.1, 49.1-2). For every proposal to be discussed and passed by the Assembly of Citizens, the Council member who had made the proposal had to be made known, as did the phyle (tribe) which had the presidency, as well as the supervisor of prytaneis. These names were recorded at the beginning of the decree. If a decree was found to be illegal, under the graphe paranomon system, it was made void and the person responsible for its introduction stood trial.

Each of Cleisthenes’s ten tribes selected fifty councillors from each deme (rural district or village) of the tribe. These councillors constituted the Council of Five Hundred. During the 5^thcentury B.C. they served on an annual basis, but during the 4^thcentury they were prohibited from holding office for two consecutive years, or serving on the Council more than twice. The members of the Council had to be Athenian citizens over thirty and belong to one of the three wealthiest classes, the pentakosiomedimnoi (men with a fortune of five hundred bushels), the hippeis (the cavalry class) or the zeugitai (the hoplite class). Before they were sworn in at the first meeting of the year, new members had to undergo an examination known as dokimasia, and at the end of their term they were subject to a review of their conduct (euthyna). The members of the Council had certain privileges: they were exempt from military obligations during the period of their service, were given special seats at the theatre and had legal immunity. After the reforms of Pericles they also received Council fees.

The Council met at the Bouleuterion every day except holidays. It was summoned by the tribe holding the Presidency and was made up of the fifty councillors of each tribe, in an order settled by lot. The Presidency was a rotating one: councillors of each tribe became Presidents (prytaneis) for thirty-five or thirty-six days, a period corresponding to the Attic month. The month was named after the tribe holding the Presidency and was equal to 1/10 of the political year. The Presidents were the most important people in their village. Every day the supervisor of the Presidents was appointed by lot. The supervisor along with the seventeen Presidents of a trittys or tribal thirds (the number corresponded to 1/3 of the number of the fifty presidents) resided and dined at the Prytaneion, probably at Tholos. In that way, every Athenian citizen had the opportunity to become supervisor of the Presidents once in his lifetime, from one sunset to the next. The supervisor had the highest executive authority, held the public seal and the keys of the sanctuaries (where the city treasure and the public archives were kept). In addition, he could become President of the both the Council of Five Hundred and of the Assembly, should an Assembly meeting coincide with the day of his presidency.