The Centuriate Assembly (Latin: comitia centuriata) 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 originally reflected military status, but later reflected 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 (the lex de imperio or "Law on Imperium"), and Censorial powers to Censors (the lex de potestate censoria or "Law on Censorial Powers"). In addition, the Centuriate Assembly served as the highest court of appeal in certain judicial cases (in particular, cases involving perduellio), and ratified the results of a Census.
Since the Romans used a form of direct democracy, citizens, and not elected representatives, voted before each assembly. As such, the citizen-electors had no power, other than the power to cast a vote. Each assembly was presided over by a single Roman Magistrate, and as such, it was the presiding magistrate who made all decisions on matters of procedure and legality. Ultimately, the presiding magistrate's power over the assembly was nearly absolute. The only check on that power came in the form of vetoes handed down by other magistrates. Any decision made by a presiding magistrate could be vetoed by a magistrate known as a "Plebeian Tribune". In addition, decisions made by presiding magistrates could also be vetoed by higher-ranking magistrates.
In the Roman system of direct democracy, two primary types of assembly were used to vote on legislative, electoral, and judicial matters. The first was the Committee (comitia, literally "going together" or "meeting place"). The Centuriate Assembly was a Committee. Committees were assemblies of all citizens, and were used for official purposes, such as for the enactment of laws. Acts of a Committee applied to all of the members of that Committee. The second type of assembly was the Council (concilium), which was a forum where specific groups of citizens met for official purposes. In contrast, the Convention (conventio, literally "coming together") was an unofficial forum for communication. Conventions were simply forums where Romans met for specific unofficial purposes, such as, for example, to hear a political speech. Private citizens who did not hold political office could only speak before a Convention, and not before a Committee or a Council. Conventions were simply meetings, and no legal or legislative decisions could be made in one. Voters always assembled first into Conventions to hear debates and conduct other business before voting, and then into Committees or Councils to actually vote.