The Primera Junta or First Assembly is the most common name given to the first independent government of Argentina. It was created on 25 May 1810, as a result of the events of the May Revolution. The Junta initially had representatives from only Buenos Aires. When it was expanded, as expected, with the addition of the representatives from the other cities of the Viceroyalty of the Río de la Plata, it became popularly known instead as the Junta Grande (Big Junta). The Junta operated at El Fuerte (the fort, where the modern Casa Rosada stands), which had been used since 1776 as a residence by the Viceroys.

This Junta—officially named the Junta Provisional Gubernativa de las Provincias del Río de la Plata a nombre del Señor Don Fernando VII (Provisional Governing Junta of the Provinces of Río de la Plata in the Name of Señor Don Ferdinand VII)—allegedly meant to govern in the name of the King of Spain, while he was imprisoned by Napoleon Bonaparte. Juntas were a form of transitional or emergency government, which attempted to maintain Spanish sovereignty, that emerged during the Napoleonic invasion in Spanish cities that had not succumbed to the French. The most important for Spanish America was the Junta of Seville, which claimed sovereignty over the overseas possessions, given the fact that the province of Seville historically had enjoyed exclusive rights to the American trade. Its claims had been rejected by Spanish Americans, and its authority was quickly superseded by a Supreme Central Junta of Spain, which included American representation.