
The Centuriate Assembly of the Roman Republic was one of the three voting assemblies in the Roman constitution. It was named the Centuriate Assembly as it originally divided Roman citizens into groups of one hundred men by classes. The centuries initially reflected military status, but were later based on the wealth of their members. The centuries gathered into the Centuriate Assembly for legislative, electoral, and judicial purposes. The majority of votes in any century decided how that century voted. Each century received one vote, regardless of how many electors each Century held. Once a majority of centuries voted in the same way on a given measure, the voting ended, and the matter was decided. Only the Centuriate Assembly could declare war or elect the highest-ranking Roman magistrates: consuls, praetors and censors. The Centuriate Assembly could also pass a law that granted constitutional command authority, or "Imperium", to Consuls and Praetors, and Censorial powers to Censors. In addition, the Centuriate Assembly served as the highest court of appeal in certain judicial cases, and ratified the results of a Census.

The Curiate Assembly was the principal assembly that evolved in shape and form over the course of the Roman Kingdom up until the Comitia Centurial organized by Servius Tullius. During these first decades, the people of Rome were organized into thirty units called "Curiae". The Curiae were ethnic in nature, and thus were organized on the basis of the early Roman family, or, more specifically, on the basis of the thirty original patrician (aristocratic) clans. The Curiae formed an assembly for legislative, electoral, and judicial purposes. The Curiate Assembly passed laws, elected Consuls, and tried judicial cases. Consuls always presided over the assembly. While plebeians (commoners) could participate in this assembly, only the patricians could vote.

Elections in the Roman Republic were an essential part to its governance, with participation only being afforded to Roman citizens. Upper class interests, centered in the urban political environment of cities, often trumped the concerns of the diverse and disunified lower class; while at times, those already in power would pre-select candidates for office, further reducing the value of voters’ input. The candidates themselves at first remained distant from voters and refrained from public presentations, but they later more than made up for time lost with habitual bribery, coercion, and empty promises. As the practice of electoral campaigning grew in use and extent, the pool of candidates was no longer limited to a select group with riches and high birth. Instead, many more ordinary citizens had a chance to run for office, allowing for more equal representation in key government decisions.

The executive magistrates of the Roman Republic were officials of the ancient Roman Republic, elected by the People of Rome. Ordinary magistrates (magistratus) were divided into several ranks according to their role and the power they wielded: censors, consuls, praetors, curule aediles, and finally quaestor. Any magistrate could obstruct (veto) an action that was being taken by a magistrate with an equal or lower degree of magisterial powers. By definition, plebeian tribunes and plebeian aediles were technically not magistrates as they were elected only by the plebeians, but no ordinary magistrate could veto any of their actions. Dictator was an extraordinary magistrate normally elected in times of emergency for a short period. During this period, the dictator's power over the Roman government was absolute, as they were not checked by any institution or magistrate.

The legislative assemblies of the Roman Republic were political institutions in the ancient Roman Republic. According to the contemporary historian Polybius, it was the people who had the final say regarding the election of magistrates, the enactment of Roman laws, the carrying out of capital punishment, the declaration of war and peace, and the creation of alliances. Under the Constitution of the Roman Republic, the people held the ultimate source of sovereignty.

The Roman Assemblies were institutions in ancient Rome. They functioned as the machinery of the Roman legislative branch, and thus passed all legislation. Since the assemblies operated on the basis of a direct democracy, ordinary citizens, and not elected representatives, would cast all ballots. The assemblies were subject to strong checks on their power by the executive branch and by the Roman Senate. Laws were passed by Curia, Tribes, and century. When the city of Rome was founded, a senate and an assembly, the Curiate Assembly, were both created. The Curiate Assembly was the principal legislative assembly during the era of the Roman Kingdom. While its primary purpose was to elect new kings, it also possessed rudimentary legislative powers. Shortly after the founding of the Roman Republic, the principal legislative authority shifted to two new assemblies, the Tribal Assembly and the Centuriate Assembly. Eventually, most legislative powers were transferred to another assembly, the Plebeian Council. Ultimately, it was the Plebeian Council that disrupted the balance between the senate, the legislative branch, and the executive branch. This led to the collapse of the republic, and the founding of the Roman Empire in 21 BC. Under the empire, the powers that had been held by the assemblies were transferred to the senate. While the assemblies eventually lost their last semblance of political power, citizens continued to gather into them for organizational purposes. Eventually, however, the assemblies were abandoned.

The Roman magistrates were elected officials in Ancient Rome.

The Roman Senate was a governing and advisory assembly in ancient Rome. It was one of the most enduring institutions in Roman history, being established in the first days of the city of Rome. It survived the overthrow of the Roman monarchy in 509 BC; the fall of the Roman Republic in the 1st century BC; the division of the Roman Empire in AD 395; and the fall of the Western Roman Empire in 476; Justinian's attempted reconquest of the west in the 6th century, and lasted well into the Eastern Roman Empire's history.

A tribus, or tribe, was a division of the Roman people, constituting the voting units of a legislative assembly of the Roman Republic. The word is probably derived from tribuere, to divide or distribute; the traditional derivation from tres, three, is doubtful.

The Second Triumvirate was the political alliance between three of the Roman Republic's most powerful figures: Octavian, Mark Antony, and Lepidus. Formally called the Triumvirate for Organizing the Republic, it was formed on 27 November 43 BC with the enactment of the Lex Titia, and existed for two five-year terms, covering the period until 33 BC. Unlike the earlier First Triumvirate, the Second Triumvirate was an official, legally established institution, whose overwhelming power in the Roman state was given full legal sanction and whose imperium maius outranked that of all other magistrates, including the consuls.

The Senate was the governing and advisory assembly of the aristocracy in the ancient Roman Republic. It was not an elected body, but one whose members were appointed by the consuls, and later by the censors. After a Roman magistrate served his term in office, it usually was followed with automatic appointment to the Senate. According to the Greek historian Polybius, our principal source on the Constitution of the Roman Republic, the Roman Senate was the predominant branch of government. Polybius noted that it was the consuls who led the armies and the civil government in Rome, and it was the Roman assemblies which had the ultimate authority over elections, legislation, and criminal trials. However, since the Senate controlled money, administration, and the details of foreign policy, it had the most control over day-to-day life. The power and authority of the Senate derived from precedent, the high caliber and prestige of the senators, and the Senate's unbroken lineage, which dated back to the founding of the Republic in 509 BC. It developed from the Senate of the Roman Kingdom, and became the Senate of the Roman Empire.

The Tribal Assembly was an assembly consisting of all Roman citizens convened by tribes (tribus).