Ranneberger was awarded an International Affairs Fellowship from the Council on Foreign Relations for his work as a Special Assistant to Under Secretary Michael Armacost from 1984 to 1985.

From 1989 to 1992, he served as Deputy Chief of Mission in Asuncion, where he was involved in supporting the post-Stroessner democratic transition.

He then became Deputy Director for Central American Affairs from 1992 to 1994, and during that time he helped oversee implementation of the peace accords in El Salvador and made efforts to end the internal conflict in Guatemala.

In July 1995, Ranneberger was appointed as the Coordinator of Cuban Affairs Ranneberger helped lead the Administration’s policy to promote a peaceful democratic transition in Cuba, in part by intensifying support for human rights activists and the development of independent civil society.

Ranneberger served as the Senior Representative on Sudan in the Bureau of African Affairs from January to August 2006.

He was confirmed by Congress to be the United States Ambassador to Kenya on June 29, 2006 and began field duties on August 11, 2006.