[1][2] A leader in the humanitarian field, Boston magazine posited that "the Harvard professor's exploits have inspired legions of followers to dedicate themselves to helping right the political, military, and environmental wrongs of the world.

[4] VanRooyen has been deployed at more than thirty countries affected by war and disaster including Somalia, Rwanda, the Democratic Republic of the Congo, Bosnia, Iraq, and North Korea with numerous non-governmental organizations (NGOs), including: Save the Children, Physicians for Human Rights, Save the Children, and Oxfam.

[7] He has also served on the board of the International Rescue Committee and as a policy advisor to the World Health Organization and United Nations Office for the Coordination of Humanitarian Affairs.

VanRooyen frequently testifies before the U.S. Congress and the United Nations on issues related to Darfur, Iraq, and the Democratic Republic of the Congo, serving as a policy adviser for governmental and non-governmental organizations alike.

[4] Domestically VanRooyen worked with the American Red Cross to provide humanitarian assistance in the wake of the September 11th attacks and as a coordinator of their field hospital response to Hurricane Katrina.