Urbanization and Revolution in Latin America studies, from a historical point of view, the classic problem of the social sciences about the political significance of the urban masses, that is, the dilemma of whether the social changes brought about by the urbanization of Latin America and the transfer of millions of people from the countryside to the city implied a threat capable of subverting the capitalist social order or whether they could be used to ensure the continuity of the system in a situation of accelerated transformation of society. The work is a history of the social technologies that were put to the test in Santiago de Chile, Buenos Aires and Mexico City in the face of the dilemmas posed by the emergence of the urban masses in the second half of the 20th century. It is a social history of the social sciences, but in the sense of applied knowledge, put to the test, reconstructed and questioned when put into play, contingently, with the historical knowledge of urban struggles. Thus, this is not a history of science and technology or of the formation of the relatively autonomous fields of knowledge that deal with cities in a narrow sense, but of how knowledge is produced, reordered and questioned when it becomes a method for managing social change staged in urban neighborhoods.