FN består af Generalforsamlingen, Sikkerhedsrådet, Det økonomiske og sociale Råd, Formynderskabsrådet, Den internationale Domstol og Sekretariatet. FN ledes af en generalsekretær, Trygve Lie (1946-1953), Dag Hammerskjöld (1953-1961), U. Thant (1962-1971), Kurt Waldheim (1971-19??), og Kofi Annan.
Sikkerhedsrådet kan, ifølge FN-pagtens artikel 41 afgøre, "hvilke forholdsregler, dog ikke omfattende anvendelsen af våbenmagt, der skal tages for at gennemføre dets beslutninger, og det kan opfordre medlemmerne af de Forenede Nationer til at iværksætte sådanne forholdsregler. Disse kan indbefatte fuldstændig eller delvis afbrydelse af økonomiske forbindelser og samkvemmet ved jernbaner, til søs, i luften, ved post, telegraf, radio og andre kommunikationsmidler samt afbrydelse af diplomatiske forbindelser".
Generalforsamlingen kan
indkaldes til specielle samlinger, eksempelvis
nedrustningssessioner.In 1950, the Security Council set up a procedure for insuring that stalemates between countries would not prevent the United Nations from carrying out its mission to "maintain international peace and security." With the United States playing an important role in its adoption, the Council adopted Resolution 377, the aptly named "Uniting for Peace" in an almost unanimous vote. Uniting for Peace provides that if, because of the lack of unanimity of the permanent members of the Security Council (France, China, Russia, Britain, United States), the Council cannot maintain international peace where there is a "threat to the peace, breach of the peace or act of aggression," the General Assembly "shall consider the matter immediately." The language of Uniting for Peace would also allow its use even if the Security Council approved the use of force against Iraq. It can be employed "if the Security Council … fails to exercise its primary responsibility for the maintenance of international peace and security."
The General Assembly can meet within 24 hours to consider such a matter, and can recommend collective measures to U.N. members including the use of armed forces to "maintain or restore international peace and security."
Siden Koreakrigen i 1950 har FN periodevis rådet over militære styrker, FN-soldater, til konfliktforebyggende arbejde. FN-pagten regulerer, hvilke vilkår som må være opfyldt for at krigsoperationer skal kunne iværksættes af medlemslandene. Kapitlene VI, VII og VIII indeholder de centrale artikler.
FN kan vedtage og erklære embargo.
FNs våbeninspektører er anvendt i forbindelse med våbenhviler og i forbindelse med krigen i Irak.
Blandt FNs underorganisationer er CD, the Committee on the Peaceful Uses of Outer Space, the UN Compensation Commission (UNCC), COPUOS, FAO ; IAEA, ILO, IMF, IPCC - Intergovernmental Panel on Climate Change, GATT, Office for Outer Space Affaires ; the UN Peacebuilding Commission ; UNCD, UNCF, UNDP ; UNEF, UNESCO, UNFPA ; UNHCR, UNICEF, UNOPS ; UNRWA ; WHO.
U.N.'s Office of Internal Oversight Services
- https://oios.un.org/
'The Office of Internal Oversight Services is the internal oversight body of the United Nations. Established in 1994 by the General Assembly, the office assists the Secretary-General in fulfilling his oversight responsibilities in respect of the resources and staff of the Organization through the provision of audit, investigation, inspection, and evaluation services. The Office aims to be an agent of change that promotes responsible administration of resources, a culture of accountability and transparency, and improved programme performance.'
Blandt FN-organisationer som har modtaget Nobels Fredspris kan nævnes FAO ; IAEA ; ILO ; UNHCR (to gange) og UNICEF.