The National Liberation Party is a political party of Costa Rica which was founded by Jose Figueres Ferrer in 1948, following the end of the Costarrican Civil War . It soon became one of the most important in the country. In 2002, for the first time in history, it lost its second consecutive election.

Some of the most dynamic and effective leaders that have presided over the country have been of the PLN. Among them are National Civil War Hero Jose Figueres Ferrer and Nobel Peace Prize Winner Oscar Arias Sanchez.

The party is a member of the Socialist International.