The Argentine section is perhaps the strongest in the world on the thought, activities, and influence of Juan Perón before, during, and after his main period in power (1946–1955). It includes his hand-written official letter of resignation from the presidency written to the Argentine military on 22 September 1955 and a handwritten document addressed at the same time to the Argentine people on the subject of his departure. The collection also includes dozens of major letters written by Perón, mostly during his years in exile to Hipólito Paz, his former foreign minister and ambassador to the United States; to Chilean congresswoman and writer María de la Cruz; to journalist colleague Américo Barrios; and to Atilio Garcia Mellid and many others. It also includes a collection of 1931 examination papers from the Argentine Colegio Superior de Guerra, heavily annotated by Professor Juan Perón, which are believed to be the earliest handwritten record of his views on domestic and international issues; two handwritten manuscripts found on Perón's desk after he was overthrown in 1955, the last documents of his main period in office; and the papers of Juan Atilio Bramuglia, a Peronist organizer, foreign minister, and in 1948 president of the United Nations Security Council.
The collection also includes a broad range of published materials covering the political, social, and economic aspects of the Perón governments, including open and underground support for and opposition to the governments and to Perón himself. The collection is particularly strong in the publications and speeches of Juan Domingo and Eva Perón. Since 1990 many materials have been collected on the administration of President Carlos Menem and his economy minister, Domingo Cavallo. A new oral history program has begun to document Argentina's return to democracy during the 1980s and 1990s.