The president of the republic is elected by universal suffrage to a 4-year term by an absolute majority of votes and supervises the affairs of the executive branch. The president appoints and supervises the Council of Ministers (members of the cabinet), coordinates government decisions, and selects government policies to be placed before the National Assembly. The National Assembly consists of 290 members elected to a 4-year term. The members are elected by direct and secret ballot from among the candidates approved to run by the Council of Guardians. All legislation from the assembly must be reviewed by the Council of Guardians. The Council's six lawyers vote only on limited questions of the constitutionality of legislation; the religious members consider all bills for conformity to Islamic principles.

In 1988, Ayatollah Khomeini created the Council for Expediency, which resolves legislative issues on which the Majles and the Council of Guardians fail to reach an agreement. Since 1989, it has been used to advise the national religious leader on matters of national policy as well. It is composed of the heads of the three branches of government, the clerical members of the Council of Guardians, and members appointed by the national religious leader for 3-year terms. Cabinet members and Majles committee chairs also serve as temporary members when issues under their jurisdictions are considered.

Judicial authority is constitutionally vested in the Supreme Court and the four-member High Council of the Judiciary; these are two separate groups with overlapping responsibilities and one head. Together, they are responsible for supervising the enforcement of all laws and for establishing judicial and legal policies.

The military is charged with defending Iran's borders, while the Revolutionary Guard Corps is charged mainly with maintaining internal security. Iran has 30 provinces, each headed by a governor general. The provinces are further divided into counties, districts, and villages.