Brandi asked a question that made me think, in my post about The Long, Long Childhood of the Greeks. If you were a legal child, did that prevent you from voting?
The answer is no, you could vote even if your father was standing right next to you. (Which he may well have been to make sure you voted the way he wanted.)
But it raised the obvious next question: what was the voting age?
It took me a while to dig out the answer, but here it is. Men who were citizens got the vote from age 18. Aristotle's Athenian Politics, Chapter 42, Section 1, courtesy of the Perseus Digital Library, says in part:
The present form of the constitution is as follows. Citizenship belongs to persons of citizen parentage on both sides, and they are registered on the rolls of their demes at the age of eighteen...
A deme was like a combination of suburb and sub-tribe.
The rule that to be a citizen both your parents had to be citizens was introduced by Pericles himself, and he got hoist on his own petard by that one. Later on, he fell desperately in love with Aspasia of Miletus, and they had a son, also called Pericles, who of course could not be a citizen because his mother wasn't. Pericles had to go to the people and beg them to overlook his own law. He got nowhere until be broke down and sobbed before the entire populace, a major event since Pericles prided himself on his public composure. The people, having had their fun, duly enrolled Pericles the Younger as a citizen.
Only men had the vote. Women were losers, I'm afraid; so were slaves (no surprise there) and resident aliens (called metics) of whom there were lots. The good news is, the franchise extended over not merely the city, but all of Attica, the quite large region of southern Greece controlled by Athens. Of course you had to be physically present in the city to vote, there being a distinct lack of internet at this stage, but people did come in for important issues.
As a percentage of total population, the franchise wasn't huge, but the amazing thing is that there was a franchise at all. This was the world's first democracy and they fiddled with the basic laws constantly to fine tune the system, which was surprisingly complex when you look at it in detail.
Wikipedia incorrectly (as usual) says that men didn't get the vote until after they'd completed their army training, but I can forgive them the error just this once because the two came closely together. Every male citizen as soon as he reached adulthood, was required to serve two years as an Ephebe (trainee-recruit) in the army. So pretty much the moment you got enrolled to vote, you were whisked off for 2 years of no doubt hellish boot camp. No exceptions. Probably the first time lots of men got to vote was when they were released from the army at age 20.
There was a higher age restriction on holding public office. You had to be 30+ years old to be an archon (civil leader), or a strategos (military leader...you'll never guess where we get our word strategy from), or be a member of the council which managed the affairs of the general assembly.
Something people in our modern democracies don't entirely get about Athens, is that back then, people were voting all the time. There was none of this modern vote-once-every-4-years-and-then-let-someone-else-run-the-country rubbish. The entire voting populace formed the entire parliament. If you didn't like the way things were going, then there was no one to blame but yourself, because you and your neighbor voted for it.
So when I say at age 18 you were enrolled to vote, what I mean is at age 18 you became a legislator in the ruling government.
There were about 40 voting days in every year. Of course not everyone could attend every assembly, so they set a quorum of 6,000 people. Imagine if your own parliament had a minimum 6,000 members!