 Derse joined the Department of State in 1981, and served in Trinidad and Tobago from 1981 to 1983.From 1985 to 1988 she followed her husband to Singapore, where he served as First Secretary of the United States Embassy in Singapore there; however, he was expelled by the Singaporean government in May 1988 for his alleged involvement with opposition politicians Francis Seow and Patrick Seong, in an incident which came to be known as the "Hendrickson affair".Her most influential role came in 1999 when, as Minister Counselor for Economic Affairs at the U.S. Mission to the European Union (USEU), she led the Mission's economic team covering U.S.-EU economic relations and served as the last U.S. Commissioner on the Tripartite Gold Commission, which adjudicated sovereign claims for Nazi gold recovered by the Allies after World War II.