Maresca has held a number of posts in the US government and served as Rector of the United Nations mandated University for Peace (UPEACE) in Costa Rica until February 2013.
During his diplomatic career, Maresca held several key positions including United States Representative to the Organization for Security and Cooperation in Europe (OSCE) between 1989 and 1992, Special Mediator for conflicts in Nagorno-Karabakh and Cyprus, and chief American negotiator for Military Confidence and Security-Building Measures. He negotiated the Helsinki Final Act of 1975 as well as the 1990 Charter of Paris for a New Europe and the Joint Declaration of Twenty-Two States, the two documents that formally ended the Cold War and converted the OSCE to a post-Cold War role. Ambassador Maresca was sent as a Special Envoy to open U.S. relations with the newly independent states from the former Soviet Union.
Prior to that, between 1986 and 1989, he held the post of Deputy Assistant Secretary of Defense.
