The forerunner of the United Nations was the League of Nations, an organization that was established in 1919, after the signing of the Treaty of Versailles, "to promote international cooperation and achieve peace and security", and to which Spain adhered as a founding country included in Annex I of the Treaty of Versailles (1920).

[2] The newly formed United Nations was initially reluctant to admit Francoist Spain because: Thus, on 12 December 1946, the General Assembly adopted Resolution 39(I),[5] which excluded the Spanish government from international organizations and conferences established by the United Nations.

[8] [7][9][10] In January 1950, The New York Times published a letter by the U.S. Secretary of State Dean Acheson that admitted that Resolution 39 had been a failure.

Throughout this period, and especially since the return of democracy following Franco's death in November 1975, Spain has been actively involved in the organization, reiterating the need for the international community to be based on the pillars of security, development and respect for human rights.

[2] Spain ranks eleventh on the scale of financial contributions to the United Nations Regular Budget and is a member of the Geneva Group, made up of the largest contributors, which carries out exhaustive monitoring of administrative and budgetary issues in the United Nations system, including the specialized agencies and international technical organizations.