Arendt claimed that violence is not part of the political because it is instrumental. Her position has generated a vast corpus of scholarship, most of which falls into the context of the realist-liberal divide. Taking these discussions as a starting point, this essay engages with violence in Arendt’s work from a different perspective. Its interest lies not in Arendt’s theory of violence in the world, but in the function that violence performed in her work, namely, in the constitutive role of violence in her thought. It argues that the concept of violence allowed Arendt to make important distinctions serving to catalyze the categories that constitute her political philosophy and, in particular, the categories of public and private. More specifically, it claims that the concept of violence in Arendt’s work is the a priori background against which both the public and private realms should be defined.