In this important contribution to political theory, Massimo Modonesi develops the thesis that a Marxist theory of political action can be developed from the notion of antagonism, defined as a distinctive feature of struggle and of the political experience of insubordination. The author argues this central idea with close reference to the concept of class struggle. He advances a theoretical proposal based on the triad subalternity-antagonism-autonomy, as well as the uneven and combined character of the processes of political subjectification. At the center of this triad, the concept of antagonism stands out as a logical principle and the core of a Marxist theory of political action. At the same time, subalternism reappears frequently, as the counter-pole of antagonistic activation and autonomous practices, and as the root of what Antonio Gramsci calls ‘passive revolutions’.