Argentina and the United States had basically no diplomatic relations towards the end of World War II. When Franklin D. Roosevelt appointed Nelson A. Rockefeller (NAR) to the State Department to plan the U.S. policy toward Latin America, he disturbed the normalization of bilateral relations. After sending a mission to negotiate with the government of Farrell and Perón, NAR pushed for the reincorporation of Argentina into the Inter-American system at the Chapultepec Conference. Soon after, he promoted the normalization of American-Argentine diplomatic relations and even the acceptance of Argentina at the San Francisco Conference. My research at the Rockefeller Archive Center (RAC) in October and November 2010, allowed me to discover unpublished documents which are very important in understanding the role of NAR in these negotiations, and also to discover his motivations, which differed from those of other senior officials at the Department of State.