Ambassador Mary Beth Leonard concluded nearly 35 years in the U.S. Foreign Service in March, 2023 as Ambassador to the Federal Republic of Nigeria with the rank of Minister Counselor. In the fall of 2023, she served as the Senior Advisor for African African Affairs at the United States Mission to the United Nations during the 78th Session of the United Nations General Assembly. She was previously the U.S. Permanent Representative to the African Union and the UN Economic Commission for Africa (2016-19) and Ambassador to the Republic of Mali (2011-2014). She also served in Cameroon, Namibia, Togo, and South Africa, and had also been Deputy Chief of Mission in Bamako. She was the Department of State’s Director for the Office of West African Affairs from 2009-2011. She served as the State Department’s recruiter for New England, and as faculty at the U.S. Naval War College.
Ambassador Leonard's service in Mali was recognized with the Department’s Diplomacy for Human Rights Award in 2013, an honor that annually recognizes a U.S. Chief of Mission who has demonstrated extraordinary commitment to defending human rights and advancing democratic principles in his or her host country. She is also a recipient of the Meritorious Presidential Rank Award.

A native of Massachusetts, Ambassador Leonard graduated magna cum laude with a B.A. from Boston University, with a major in economics and a minor in French. In 1988, she earned a master’s degree in international relations, with an emphasis on African studies, from the Johns Hopkins University School of Advanced International Studies. In 2004, she received a Master of Security and Strategic studies from the U.S. Naval War College, with distinction. She speaks French, Spanish, Afrikaans, and Dutch.