The Republican Constitution of Dubrovnik was strictly aristocratic. The population was divided into three classes: nobility, citizens, and artisans or plebeians. All effective power was concentrated in the hands of nobility. The citizens were permitted to hold only minor offices, while plebeians had no voice in government.

Marriage between members of different classes of the society was forbidden. The administrative bodies were the Grand Council (supreme governing body) and the Small Council (executive power) (from 1238.) and the Senate (from 1253). The head of the state was the Duke, elected for a term of office for one month. Grand Council (Veliko vijeee) consisted of exclusively members of the aristocracy; every noble took his seat at the age of 18. Small Council (Malo vijeee) consisted first of 11 members and after 1667 of 7. The Small Council was elected by the Knez or Rector. The Senate (Vijeee umoljenih) was added in 1235 as a consultative body. It consisted of 45 invited members (over 40 years of age). While the Republic was under the rule of Venice the Rector was Venetian, but after 1358 the Rector was always a Ragusan. The length of the Rector's service was only one month and a person was eligible for reelection after two years. The rector lived and worked in Rector's Palace but his family remained living in their own house. The government of the Republic was liberal in character and early showed its concern for justice and humanitarian principles, e.g. slave trading was abolished since 1418.