Sarah Sewall (born August 21, 1961) is Executive Vice President for Policy at In-Q-Tel, a strategic investor for the national security community.

In partnership with U.S. military leaders, she helped revise U.S. counterinsurgency doctrine, led groundbreaking field assessments of U.S. civilian casualty mitigation efforts, and created new operational concepts for halting mass atrocities.

She worked as a military analyst for the House Democratic Study Group before becoming Senate Majority Leader George J. Mitchell's Senior Foreign Policy Advisor in 1987.

Sewall joined Harvard's Kennedy School of Government, where she launched the Project on the Means of Intervention, a ground-breaking forum for military and humanitarian actors to engage contentious questions about the conduct of war.

[4] She collaborated with General David Petraeus to revise U.S. counterinsurgency doctrine, making humanitarian issues central to the project, and writing an influential introduction to Field Manual FM 3-24.

[5][6] Sewall subsequently launched the MARO Project, a partnership with the U.S. Army Peacekeeping Institute, to develop an operational concept for intervening to halt mass atrocities.

She helped lead his pre-election transition effort and following the election directed the reviews of all national security, foreign policy, intelligence and development agencies before returning to Harvard.

[17] Sewall's personal diplomatic engagement focused on preventing conflict, terrorism, and atrocities in countries such as Nigeria, Guatemala, the Democratic Republic of Congo, Indonesia, East Africa, Bangladesh, and Kazakhstan.