As per the Puerto Rico Constitution, a democratic and republican form of government is set, divided into three branches: legislative, executive, and judicial, each of equal importance and equally subordinated to the sovereign power of the people.

The legislative branch consists of a bicameral Legislative Assembly with a Senate (27 members) and a House of Representatives (51 members). A constitutional provision requires that total membership in the Assembly be expanded, as necessary, to increase minority representation whenever one-party controls more than two thirds of seats. A Resident Commissioner, who serves as the island's sole delegate to the U.S. Congress, holds limited powers as a member of the U.S. House of Representatives. Executive authority is vested in a governor.

The Island is divided into 78 municipalities, each led by a mayor and municipal assembly. All of the aforementioned positions are elective, with balloting conducted every four years in November. Victorious candidates take office the following January. Resident U.S. citizens, age 18 and older, are eligible to vote; voter turnout consistently exceeds 80% of the electorate.

The Governor appoints executive branch and public corporation leadership positions, under a highly centralized structure. The Secretary of State (who serves as acting governor in the chief executive's absence) must be confirmed by a majority vote of both chambers of the Legislative Assembly; other senior nominees require confirmation only by the Senate.

The Constitution vests judicial power in the Puerto Rico Supreme Court, and such lower courts as may be established by law. Members of the judicial branch are nominated by the governor and confirmed by the Senate. Decisions rendered by Municipal, District, and Superior courts may be appealed, until they reach the Supreme Court composed of nine justices. Lower court judges serve fixed terms; Supreme Court justices serve until retirement at age 70. The court system is led by the Chief Justice of the Supreme Court.

Seven judges, nominated by the U.S. President and confirmed by the U.S. Senate, serve on Puerto Rico's Federal District court. Also serving are three senior judges and four magistrate judges. Its decisions may be appealed through the federal court system to the U.S. Court of Appeals for the First Circuit, and to the U.S. Supreme Court. Decisions of the Puerto Rico Supreme Court may be appealed directly to the U.S. Supreme Court under certain limited circumstances.