Because of the large amounts of material available on Spartan society, this essay is simply designed as an overview. All of this information, and more, can be found in any text relating to ancient Greece.
In the Dark Ages (the era after the fall of Myceneae) Dorians built Sparta as a military encampment, and it remained as such until the Spartans incorporated nearby settlements on the Laconian plain.
By the end of the Dark Ages, Sparta had become pre-eminent in Greece. Spartan lords endeavored to conquer more land, for their population was growing exceedingly large. Those whom the Spartans conquered were enslaved and called Helots, and they eventually revolted against the small Spartan army and Sparta herself was almost destroyed. In light of this, King Lycurgus established a military aristocracy .
In the early 7th century BCE, Lycurgus rose to power. He was the great lawmaker of Sparta, having written its constitution and laying down the law that made Sparta such a military power. Under Lycurgus' laws, Sparta had political equality for all Spartan citizens. At the time Sparta controlled all of the Peloponnesos.
Managing Sparta was no small task. Thanks to its military might, there were massive amounts of conquered territory, which, though citizens managed it privately, remained the property of the state. Most subjects of those conquered lands were enslaved by the Spartan government and were known as helots. Though the helots were viewed as state property, individual Spartans – presumably those who managed the conquered land – took half the responsibility of the helots' protection, while the other half reverted to the state.
Because of the amount of conquered territory under Spartan rule, there were numerous helots. The helots identified themselves as one race, although they previously belonged to different city-states. This unified them and sowed seeds of discontent. Helots' unity made the risk of an uprising a very real possibility, which furthered Sparta's drive to remain a military state. As well as acting as a deterrent, Spartan military power would provide the means to quash any rebellion.
Not all natives of subjugated lands were reduced to the position of being helots. Some of the more important communities in conquered regions were given some level of independence in their own domestic affairs. These peoples were called perioikoi (which translates as "neighbors") and received somewhat better treatment than helots. In spite of their better treatment, however, these peoples were not happy to be under Spartan rule, even if they were less likely to rise up against Sparta.
Sparta's Militarism and Politics
From the ages of seven to 60, Spartan males were required to serve in the military. During that time, they lived in military barracks. After twenty-five years of service, it was common for them to spend their days in military training and evenings with other military companions. This military lifestyle made a home life next to impossible. The men weren't allowed to marry until the age of 20 (which some took wives by force), but were unable to have a household until the age of 30. Spartan women were treated unusually well, they had many rights and were not subjected to the common roll of women found in other civilizations, namely, stay at home and keep the children. Spartans citizens in general had a great deal of freedom.
Because Sparta's military state was so firmly established, it was sufficient to maintain a tradition of a military monarchy. Other poleis began with this form of leadership, but grew away from it as time passed. Sparta's kingship was hereditary, but also dual; that is to say, there were two kings from two different families. Sometimes these kings got on well and worked well together, but sometimes, of course, they did not.
The Spartan Constitution
Under Lycurgus' constitution, Spartan citizens did have some basic rights. The constitution also mapped out Sparta's political structure. There were always two kings, both military leaders. The kings worked with a council of aristocrats referred to as Gerousia. The Gerousia also handled political and judicial decisions. Another governing body was the homoioi ("equals"). The homoioi was comprised of Spartan citizens who had survived their required military service, received state land (conquered territories) with helots to work it, and continued to obey Spartan rules. This assembly met regularly and made final decisions on most of the important issues related to Spartan government. Also there were the 'ephorites', the spiritual leaders with a 'connection' to the Gods, which had the power to dispose of a King, or over-turn his will.
The Spartan Citizen
In Sparta, a citizen was a member of society who was automatically entitled to certain – albeit few – rights Citizens also shared a basic sense of community. That this sense was based on fear of helot uprisings or the desire to profit from them (or both) wasn't important. This communal equality, however, was a minimum. That all Spartans owned their land privately while others had been granted use of state land was irrelevant. It didn't matter that some were high-ranking nobleman and others were 'mere mortals' as all were Spartan citizens, so all enjoyed those same basic rights.