The public rites of the Religio Romana were performed and controlled by a number of different priestly Colleges and other special priests and magistrates. Those priestly organizations that ranked below the Collegia were known as Sodalicia, and there were many 'independent' priests of various cults who bore the title of 'Sacerdos' (the Latin term for priest). In addition, there were a number of priesthoods of well-established 'foreign' cults, such as the cult of Isis, Cybele and Mithras.

Priests served a specific deity and were responsible for the care of the temple and the public rites and observances concerned with that deity. However, priests were also free to worship other deities as they wished, as long as their priestly obligations were met.

Priests in the Greek and Roman world were generally appointed for life, or for as long as the individual wished to serve, although some priesthoods were only allocated for a year at a time. Normally, state priests were appointed in some way by the state, often by actual election. On the other hand, many 'independent' priesthoods could be chosen by existing members of that priesthood from suitable candidates. Being a priest did not necessarily exclude the individual from participating in public life; often the opposite was the case, with the holding of a priesthood proving to be a useful tool in an individual's political career. Some of the more senior priesthoods did carry an array of prohibitions and taboos that might interfere with political aims, although an aspiring politician could always find ways around this if he was determined enough.

The four most important state colleges were as follows:

The Collegium Pontificum (College of Pontiffs)

Collegium Augurum (College of Augures)

Septemviri Epulones

Quindecimviri Sacris Faciundis

In addition to the four major colleges above, there were a large number of other, lesser colleges and priesthoods directly supported by the state although we are only aware of a small number of them.

Sacerdotes (minor priesthoods)

While members of the senior colleges of the city of Rome were recognisable by particular forms of dress, such as the distinctive scull-cap worn by Flamines, this was not the case with the 'everyday' priests i.e. Sacerdotes, who made do with the toga, that being the formal dress of the Roman world. The only distinctive feature was that the toga was pulled up to cover the top of the head during solemn religious ceremonies. This was the usual observance on more formal occasions when people wished to show their respect for the gods, such as when preparing to perform a sacrifice, entering a temple, approaching a grave and so on. It was the use of the toga for religious ceremonies that would in time give rise to the distinctive garments worn to this day by Bishops and other members of the Clergy.