How many could serve in the athenian assembly?

The Athenian assembly is open to all male citizens of athens.

The Athenian Assembly did have a more selective portion of government known as The Council of 500. The Council of 500, consisted of 500 citizens, 50 from each of the ten tribes that made up the area, and who were chosen through a lottery system. These chosen citizens would serve for a year and mainly prepared the agenda for the assembly meetings.