This article is an account of various institutional and social attempts to clarify both the events and the reasons that led to the massacre of October 2, 1968. The work done by the Special Prosecutor's Office for Social and Political Movements of the Past is reported, as well as, fundamentally, of the documentaries El grito (Leobardo Lopez Aretche, 1968), Diaz Ordaz y el 68 (Krauze, 1998) and Tlatelolco. Las claves de la masacre (Mendoza, 2003, in the defense of the memory of such a significant event.