[1][2] Gillespie spent over thirty years in the United States foreign service as a specialist in Latin American and Caribbean affairs.

[1] He later studied at the Maxwell School of Public Affairs at Syracuse University and the National War College in Washington, D.C.[1] Gillespie served as a United States Army officer in Europe from 1958 until 1962.

[1] He began his career in the Foreign Service in 1965, when he was made regional security officer at the Embassy of the United States in Manila in the Philippines.

[1] He was later posted in a variety of positions around the world including the United States NATO mission, Mexico City and Managua, Nicaragua.

[1][3] Gillespie headed the United States public relations task force to gain Congressional support for the North American Free Trade Agreement (NAFTA).