Born in Kumasi, Ghana, the scion of a family of Fante chieftains, he studied at Macalester College, St. Paul, Minn. (grad. 1961), and the Massachusetts Institute of Technology (M.A., 1972). Annan began working for the United Nations in 1962 (with the World Health Organization) and, except for a stint as head of Ghana's tourist ministry (1974–76), has been with UN bodies ever since. He has special expertise in the areas of refugees and peacekeeping and in 1990 negotiated the release of UN staff and Western hostages held by Iraq following the invasion of Kuwait. Named (1993) undersecretary-general for peacekeeping operations, he was a special representative to the former Yugoslavia (1995–96), overseeing the transfer of peacekeeping duties from UN forces to NATO. His tenure during this period was marred by the failure of the United Nations, its members, and its peacekeeping forces to prevent the atrocities that occurred in Rwanda and Bosnia.
In 1997, Annan succeeded Boutros Boutros-Ghali as secretary-general, becoming the first sub-Saharan African to hold the office; he was elected to a second five-year term in 2001. Accessible and affably candid, combining idealism with realism, he has generally been an effective consensus-builder. Annan has particularly emphasized the UN's traditional obligations in the area of human rights and the newer challenges of the HIV/AIDS pandemic and international terrorism. He has been quite successful at streamlining UN bureaucracy and controlling its budget, improving strained relations with the United States, and working cooperatively with international organizations and corporations. Annan also has favored overhauling the United Nations, particularly the Security Council, to make it more representative of the UN's membership and to increase the organization's effectiveness. He, along with the United Nations, was awarded the Nobel Peace Prize in 2001.
In 2002–3 Annan worked unsuccessfully to resolve the division of Cyprus, and in the same period his work as secretary-general was made more difficult by strong differences among the permanent members of the Security Council concerning how to handle Iraq's resistance to complying with UN weapons inspections and by the Anglo-American invasion of Iraq that began in 2003. He has subsequently publicly emphasized the need for individual nations to support the United Nations and work through it instead of unilaterally and the need for revamping the Security Council.
In 2004 he publicly criticized the U.S. invasion of Iraq as having been illegal. Those comments were seen as contributing to subsequent calls for his resignation by conservative Republicans in the United States because of the United Nations' failure to prevent corruption in the Iraq oil-for-food program; UN staff and Annan's son were implicated as the investigation progressed. Other nations, however, remained strong supporters of Annan.