Their duties, which were very extensive and very important, may be divided into three classes, all of which, however, were closely connected and are described as follows:
Roman Censor - Taking the Census
The first and most important duty of the Censor was to take the Census. This was not simply a list of the population, according to the modern use of the word, but a valuation of the property of every Roman citizen. This valuation was necessary, not only for the assessment of the property-tax, but also for determining the position of every citizen in the state, which was regulated, in accordance with the constitution of Servius Tullius, by the amount of his property. Accordingly, the Censors had to draw up lists of the Classes and Centuries. They also made out the lists of the Senators and Equites, striking out the names of all whom they deemed unworthy, and filling up all vacancies in the Senate.
Roman Censor - Control over Conduct and Morals
The Censors possessed a general control over the conduct and morals of the citizens. In the exercise of this important power they were not guided by any rules of law, but simply by their own sense of duty. They punished acts of private as well as public immorality, and visited with their censure not only offences against the laws, but every thing opposed to the old Roman character and habits, such as living in celibacy, extravagance, luxury, etc. They had the power of degrading every citizen to a lower rank, of expelling Senators from the Senate, of depriving the Equites of their horses, and of removing ordinary citizens from their tribes, and thus excluding them from all political rights.
Roman Censor - Administration of Finances
The Censors also had the administration of the finances of the state, under the direction of the Senate. They let out the taxes to the highest bidders for the space of a lustrum, or five years. They likewise received from the Senate certain sums of money to keep the public buildings, roads, and aqueducts in repair, and to construct new public works in Rome and other parts of Italy. Hence we find that many of the great public roads, such as the Via Appia and Via Flaminia, were made by Censors.