Ellison is a senior fellow in the Asia Program at The German Marshall Fund of the United States (GMF). She previously served as a foreign service officer at the U.S. State Department where she was special assistant to Undersecretary of State for Political Affairs Wendy Sherman, advising her on Asia-Pacific and economic issues. She also served as senior advisor to Special Representative for North Korea Ambassador Sung Kim. She has broad experience working on Northeast Asia, including the U.S.-China relationship and efforts to address North Korea’s nuclear programs. Ellison has served in the office of Korean Affairs and as the political-military officer in the office of Chinese and Mongolian Affairs, where she was responsible for a range of nonproliferation and arms control issues. She also served as the State Department’s lead on U.S.-China military and security issues with the Department of Defense. Ellison also worked as a senior policy advisor for China in the State Department's Global Engagement Center, coordinated U.S.-Russia issues in the Bureau of Legislative Affairs, and was a fellow in the United States Senate. She served overseas in Taipei and Moscow. Prior to joining the State Department, Ellison worked on the Europe team at the Department of Justice, Office of International Affairs, Criminal Division, and at the Delegation of the European Union in Washington. She has working knowledge of Chinese, Russian, and Italian. She received her master's degree in German and European studies from Georgetown University's School of Foreign Service and a bachelor's degree in political science from Wake Forest University.