The United States Naval Institute (USNI), based in Annapolis, Maryland, is a private, non-profit, professional military association that seeks to offer independent, nonpartisan forums for debate of national defense and security issues. In addition to publishing magazines and books, the Naval Institute holds several annual conferences.

Established in 1873, the Naval Institute claimed "almost 50,000 members" in 2020, mostly active and retired personnel of the United States Navy, Marine Corps, and Coast Guard. The organization also has members in over 90 countries.

The organization has no official or funding ties to the United States Naval Academy or the U.S. Navy, although it is based on the grounds of the Naval Academy through permission granted by a 1936 Act of Congress.

The Naval Institute's mission is "to provide an independent forum for those who dare to read, think, speak, and write to advance the professional, literary, and scientific understanding of sea power and other issues critical to global security". The Institute also has a Vision of "[g]iving voice to those who seek the finest Navy, Marine Corps, and Coast Guard."