The society of the Roman Republic and Roman Empire was made up of several levels. At the top were the patrician classes of senator and equestrian. The commoner classes of plebeians, freed peoples, and slaves had fewer opportunities in life. However, these social and political classes maintained order and structure in Roman culture. They created the first socially mobile culture in history.

The Roman emperor held the title of princeps senatus (chief senator) and could appoint new senators, preside over the Senate, and propose new legislation. The real power of the Senate was in its judicial functions, mainly its right to crown the new emperor.

Senators were considered a political class of citizen. The Senate was made up of 600 men who were either the sons of senators or Roman citizens over the age of 25 with military and administrative experience.

The senate class included all men who served in the Senate and their families. These were mostly nobles or families whose ancestors included at least one elected consul. The first male in each family elected to the position of consul was given the title novus homo, meaning "new man".

In order to be considered a senator a Roman citizen had to accumulate 1 million sesterces of wealth and property. Senators were granted special privileges, priority seating at sporting events and theater productions, and the right to hold the highest judicial offices.

Senators wore a gold senatorial ring and a tunica clava with a five-inch-wide purple stripe on the right shoulder. Children of these patricians often had private tutors to educate them. They even had their own bedrooms, toys, and slaves.

Families of senators usually had two homes, one in the city for business and one in the countryside for leisure, run by slaves. These homes usually had comforts such as running water, sewage, luxury furniture, and private baths.

Wealthy patricians would display gold drinking and eating vessels as well as intricate mosaics decorating the walls. They would entertain political and social guests at large banquets, often accompanied by music and dancing.

Despite these privileges senators had several restrictions placed on them. Serving the republic or the empire earned them no salary. They could not personally engage in nonagricultural businesses. They were also forbidden to practice trade or bid on public contracts.

Equestrians were the lower social group among the patricians. The basis for this class was economic in nature. A citizen had to possess 400,000 sesterces of wealth during the rule of Augustus Caesar to become an equestrian.

Emperor Augustus reorganized this social class into a military class. Equestrians were the "knights" of the Roman Empire’s cavalry and were granted a "public horse" with which to defend Rome.

Equestrians were either landed plebeians or the sons of senators who had not yet entered the quaestorship at 25 years of age. Citizens of this class also had special privileges that even the senators did not have: They were allowed to be merchants and commercial traders.

Equestrians held civil service jobs such as tax collector, banker, exporter, and administrator of public contracts. They displayed their rank on a white tunic with a one-inch-wide purple stripe over the right shoulder (the angusti clavi). Equestrians rarely became senators.

Plebeians were the lowest class of free citizens. They were the working class of Rome and the main taxpayers. Most jobs were hereditary, and they usually worked as subsistence farmers or as sharecroppers of wealthy patricians. They could also be bakers, artisans, masons, or carpenters.

None of these occupations paid very well, and most plebeians struggled to provide for their family. Plebeians usually lived in apartment homes called insulae. These homes were usually built of wood and were extremely susceptible to fire since running water was not available.

As the insulae were without kitchens, families would purchase meals consisting of coarse bread, bean or pea soup, porridge, and, if the family saved enough, chicken or rabbit once a month. Plebeians lived in very unsanitary conditions: Two families often shared one-room apartments, and chamber pots were often emptied out into the street below.

There were very few ways for a plebeian to advance socially. The first was to save enough sesterces to become an equestrian. Another way to advance was to be adopted by a patrician family.

Plebeians could earn equestrian titles by achieving any of the three highest military awards: Coronae Graminea, Civica, or Aurea. The final opportunity for social advancement was in politics.

Plebeians could seek election as a tribune of the plebs. He was elected by the Assembly of the Citizens and was the only plebeian allowed to participate in Senate meetings. After a six-month term, tribunes automatically became a member of the Senate and the equestrian order.

Roman social and political classes provided the world with new concepts of citizenship. These concepts included placing limitations on the upper class as well as opportunities for the lower classes to advance themselves. They revolutionized the way the Western world looked at society.