This article analyzes the World Conference of Solidarity with Chile, held in Madrid between November 9 and 11, 1978, and the actions of Chilean diplomacy in the face of this act contrary to the Chilean civil-military dictatorship. For this, and beyond the theoretical framework on which it rests, extensive heuristic and hermeneutical work is carried out on Chilean diplomatic documentation. This publication thus makes it possible to venture certain proposals not only about this conference, but also about the actions and limitations of diplomacy in times of dictatorship.