According to the Laws of Solon, in Athens there were four citizen classes. Each class had special public and martial tasks. There were two non-citizen classes; the metic class, or resident aliens, and, of course, slaves. Social mobility was official discouraged. A child was considered the class of their father and stayed in that class their whole lives.
Women were not considered citizens, no matter which class they belonged to.
The upper class in Athens was the Pentacosiomedimni, or the 500 measures providers. The Pentacosiomedimni were the richest group in the city, with their lands that produced 500 measures of either fruits, grains, wine or olive oil per year. This class had the greatest political power in the city. A member of the Pentacosiomedimni could serve on the supreme council of state: the Areopagus. Militarily, only a member of this class could be elected as one of the ten strategoi, or generals. Also, only one of the Pentacosiomedimni could be selected to be a captain of one of the 300 Athenian Navy triremes and would also be responsible for the maintenance of the ship and its crew. This particular military duty was so expensive that the selected man would be relieved of all other civic responsibility and other taxes for at least a year. This class would also serve as a cavalryman, or hippias, and in some cases, such as Pericles, even “went hoplite” by fighting as a heavy infantryman or hoplite.
The next richest class was the Hippada Teluntes, or horse breeders, sometimes called the Knights. This class had enough income to support a horse, or at least 300 measures of agricultural goods per year. Politically, they could also serve on the Areopagus, like the Pentacosiomedimni, but could not be selected as a general. Militarily, this class served as cavalrymen, or hippias, or as hoplite infantry, if they wanted.
The next class was the Zeugitai, or yoked men. The Zeugitai had to have at least 200 measures of agricultural produce per year and could afford a yoke of oxen to plow their fields. This group had their own governmental body, the Council of the 400. This body had veto power over the decisions of the aristocratic council of state, much like a lower house in a two house legislature. The Zeugitai were the hoplite class. They provided their own heavy shield and armor and fought in the ranks of the phalanx. The name ‘yoked men’ name could also come from their military duty of hoplites, as they were ‘yoked together’ in the phalanx.
The last citizen class was the Thetes, which produced below 200 measures of goods per year and were usually craftsmen or day laborers. Civically, the Thetes were forbidden from holding any political office. However, they could sit in the Popular Assembly, which could discuss and decide only on certain internal issues. Further, they could elect local officials, but not serve as these officials, and they served on the juries for any public trials. Militarily, the Thetes served as light infantry, since they could not afford to buy the hoplite panoply. They were the slingers, archers and javelin men. They also served as rowers in the Athenian navy.
A special note on Metics: They were generally urban tradesmen or traders. Some of them became wealthy. In the extreme circumstances of the Peloponnesian War, Metics were allowed to buy the hoplite weapons and armor and to serve guarding the walls of Athens.
Plutrach, Lives of Noble Grecians and Romans: Solon.
G. E. M. De Ste. Croix, Athenian Democratic Origins and Other Essays (Oxford; Oxford University Press, 2004).
Thucydides, History of the Peloponnesian War