When the Roman Republic was founded in 509 BC, the Roman people were organized on the basis of the curia. At the time, all Roman people were divided amongst a total of thirty Curia. The Curia were organized on the basis of the family, and thus the ethnic structure of early Rome. Each Curia even had its own festivals, gods, and religious rites. The thirty Curia would gather into a legislative assembly, the Curiate Assembly (comitia curiata). This assembly was created shortly after the founding of the city in 753 BC, and formally elected new Roman kings. During this time, plebeians had no political rights. Each plebeian family was dependent on a particular patrician family. Thus, each plebeian family belonged to the same Curia as did its patrician patron. While the plebeians each belonged to a particular Curia, only patricians could actually vote in the Curiate Assembly.
Before the first plebeian secession (in 494 BC), the plebeians probably did gather into their own assembly on the basis of the Curia. However, this assembly probably had no political role until the offices of Plebeian Tribune and Plebeian Aedile were created that year, in order to end the secession. As a result of the plebeian secession, the patrician aristocracy formally recognized the political power of the Plebeian Tribune. When they legitimized the power of the plebeian tribune, they legitimized the power of the assembly (the "Plebeian Curiate Assembly") that the Plebeian Tribune presided over. This "Plebeian Curiate Assembly" was the original Plebeian Council. After 494 BC, the "Plebeian Curiate Assembly" would always be presided over by a Plebeian Tribune. This assembly would elect the Plebeian Tribunes and the Plebeian Aediles, and would pass legislation (plebiscita) that would only apply to the plebeians.
During the later years of the Roman Kingdom, the king Servius Tullius enacted a series of constitutional reforms. One of these reforms resulted in the creation of a new organizational unit with which to divide citizens. This unit, the Tribe, was created by Tullius to assist in future reorganizations of the army". Its divisions were not ethnic (as the divisions of the Curia were), but rather geographical. Tullius had divided the city into four geographical districts, each encompassing a single Tribe. Between the reign of Tullius and the late third century BC, the number of Tribes would expand from four to thirty five. However, by 471 BC, the plebeians decided that organization by Tribe granted them a level of political independence from their patrician patrons that the Curia did not. Therefore, around 471 BC, a law was passed, which allowed the Plebeians to begin organizing by Tribe. Thus, the "Plebeian Curiate Assembly" began to use Tribes, rather than Curia, as its basis for organization. As such, the Plebeian Council transitioned from its prior status as a "Plebeian Curiate Assembly" to its new status as a "Plebeian Tribal Assembly".
The only difference between the Plebeian Council after 471 BC and the ordinary Tribal Assembly (which also organized on the basis of the Tribes) was that the Tribes of the Plebeian Council only included plebeians, whereas the Tribes of the Tribal Assembly included both plebeians and patricians. However, almost all Romans were always plebeians. Therefore, the principal differences between the Plebeian Council and the Tribal Assembly were mostly legal, rather than demographic. These legal differences derived from the fact that Roman Law didn't recognize an assembly consisting of only one group of people (plebeians in this case) from an assembly consisting of all of the People of Rome. Over time, however, these legal differences were mitigated with legislation.
The Plebeian Council elected two plebeian officers, the Tribunes and the Aediles, and thus Roman law classified these two officers as the elected representatives of the plebeians. As such, they acted as the presiding officers of this assembly.
The creation of the office of Plebeian Tribune and Plebeian Aedile marked the end of the first phase of the struggle between the plebeians and the patricians (the Conflict of the Orders). The next major development in this conflict occurred through the Plebeian Council. During a modification to the original Valerian law in 449 BC, Plebiscites acquired the full force of law, and thus applied to all Romans. Before this point, Plebiscites had only applied to Plebeians. By the early 4th century BC, the plebeians, who still lacked any real political power, had become exhausted and bitter. In 339 BC, the plebeians facilitated the passage of a law (the lex Publilia), which brought the Conflict of the Orders closer to an ultimate conclusion. Before this time, any bill passed by any assembly could only become a law after the patrician senators gave their approval. This approval came in the form of an decree called the auctoritas patrum ("authority of the fathers" or "authority of the patrician senators"). The lex Publilia required the auctoritas patrum to be passed before a law could be voted on by one of the assemblies, rather than after the law had already been voted on. It is not known why, but this modification seems to have made the auctoritas patrum irrelevant. Thus, the Plebeian Council became independent of the patrician aristocracy in everything but name.
By 287 BC, the economic condition of the average plebeian had become poor. The problem appears to have centered around wide-spread indebtedness. The plebeians demanded relief, but the senators, most of whom belonged to the creditor class, refused to abide by the demands of the plebeians. The plebeians quickly seceded to the Janiculum hill, resulting in the final plebeian secession. To end the secession, a plebeian dictator (Quintus Hortensius) was appointed, who ultimately passed a law called the "Hortensian Law" (lex Hortensia). The most significant component of this law was the fact that it ended the requirement that an auctoritas patrum be passed before any bill could be considered by either the Plebeian Council. The importance of the this law was in that it removed from the Patrician senators their final check over the Plebeian Council. The lex Hortensia, however, should not be viewed as the final triumph of democracy over aristocracy. Close relations between the Plebeian Tribunes and the senate meant that the senate could still exercise a great degree of control over the Plebeian Council. Thus, the ultimate significance of this law was in the fact that it robbed the patricians of their final weapon over the plebeians. This ended the Conflict of the Orders, and brought the Plebeians to a level of full political equality with the patricians.
The Plebeian Council did survive the fall of the Roman Republic, however it quickly lost its legislative, judicial and electoral powers to the senate. By virtue of their statuses as perpetual Tribunes, both Julius Caesar, as well as his successor, the Emperor Augustus, always had absolute control over the Plebeian Council. The Plebeian Council disappeared shortly after the reign of the Emperor Tiberius.