Ambassador Marc Grossman served as the Under Secretary of State for Political Affairs, the State Department's third ranking official, until his retirement in 2005 after 29 years in the US Foreign Service. As Under Secretary, he helped marshal diplomatic support for the international response to the attacks of September 11, 2001. He also managed US policies in the Balkans and Colombia and promoted a key expansion of the NATO alliance. As Assistant Secretary for European Affairs, he helped direct NATO's military campaign in Kosovo and an earlier round of NATO expansion. Ambassador Grossman was the US Ambassador to Turkey 1994 – 1997.

Ambassador Grossman was a Vice Chairman of The Cohen Group from July 2005 to February 2011. In February, 2011 President Obama and Secretary of State Clinton called Ambassador Grossman back to service as the US Special Representative for Afghanistan and Pakistan. Ambassador Grossman promoted the international effort to support Afghanistan by shaping major international meetings in Istanbul, Bonn, Chicago and Tokyo. He provided US backing for an Afghan peace process designed to end thirty years of conflict and played an important part in restoring US ties with Pakistan. He returned to The Cohen Group in February, 2013. Ambassador Grossman is Chairman of the Board of the Senior Living Foundation of the Foreign Service. He is a Trustee of the German Marshall Fund of the United States, the UC Santa Barbara Foundation, and Robert College of Istanbul. Ambassador Grossman is Vice Chair of the American Academy of Diplomacy. In 2013, Ambassador Grossman was Kissinger Senior Fellow at the Johnson Center for the Study of American Diplomacy at Yale University.

Raised in Los Angeles, California, Ambassador Grossman has a BA in Political Science from the University of California, Santa Barbara and an MSc in International Relations from the London School of Economics and Political Science.