The King
Were "divinely ordained" humans, and the pinnacle of social order. The word of the king was law, and they were usually the head of the army. A king could sometimes also be a priest.
The Priests
The priests were the "upper - class" of the society. Were influential because of their relationships with the gods, and the importance of religion in every day life. They also ran the schools, and were considered the doctors of their time.
The Scribes
The scribes had influence because they were the educated class, and could read and write. To become a scribe one had to undergo training and complete a specific program. They were nearly always men and worked for the palace, the government, the army, or set up their own businesses.
The Merchants and Artisans
These were the people that invented cuneiform to document trade deals. They traded ideas throughout the Tigris and Euphrates Rivers, and produced the wealth that made civilization possible. Some would lead groups with barley to Asia minor, and return with timber and metal. They also worked materials into tools, weapons, and jewelry. To keep track of the trade they did, they invented a calendar based on the phases of the moon (12 months with leap years).
The Commoners
The "lower - class" of the civilization, and about 85% of them were farmers. The tradesmen, the non - farmers, were payed uniform wages. They had very close family ties, and women had more rights than in other social orders. The son's were usually taught their father's trade and the daughter's were taught to take care of the household.
The Slaves
Although they were at the bottom, the slaves were generally treated well. They were identified by their specific hair cut. They had no rights and were owned by other people. Some were prisoners of war, and other were people who couldn't pay their debts. Sometimes they were even offered to pay off debt. People would raid the hills for slaves from the "Hill People" tribes. The laws did not protect them.