The secretary of state of Puerto Rico leads all efforts that promote the cultural, political, and economical relations between Puerto Rico and foreign countries, and other jurisdictions of the United States. The post was created by Article IV of the Constitution of Puerto Rico which merely establishes that the secretary serves as acting governor when the governor is unable to perform his duties—a post similar to that of a lieutenant governor in U.S. politics. In recent times, however, the post has evolved into one similar to that of a foreign minister. Today, the secretary is the officer in charge of Puerto Rico's foreign relations, albeit under the consent of Congress or the U.S. Department of State due to Puerto Rico's political status.

The Constitution of the Commonwealth of Puerto Rico is the controlling government document of Puerto Rico. It is composed of nine articles detailing the structure of the government as well as the function of several of its institutions. The document also contains an extensive and specific bill of rights. It was ratified by Puerto Rico's electorate in a referendum on March 3, 1952, and on July 25, 1952, Governor Luis Muñoz Marín proclaimed that the constitution was in effect. July 25 is known as Constitution Day.