Despite the extensive interest in Hannah Arendt’s ideas and the equally prolific literature on forgiveness—in which Arendt is regarded as a pioneer in claiming forgiveness to be of political significance—there has to date been no monograph on this aspect of her thought. The purpose of this doctoral dissertation is to provide a comprehensive exploration of Arendt’s account of forgiveness, its development, and its place and role in Arendt’s thought as a whole. To achieve this, I inquire into Arendt’s writings on guilt and responsibility too; for after all, guilty humans are what makes the question of forgiveness relevant. Moreover, countering the conventional dismissal of Arendt’s early work as “unworldly”, I argue that Arendt’s project of recovering the public world of politics was not only a political but also a philosophical project. Already in her 1928 dissertation on Augustine, Arendt began to grapple with Martin Heidegger’s notions of Mitsein and in-der-Welt-sein, and to develop her corrective political notion of worldliness as “being-in-the-world-with.” Arendt’s dissertation can be read, then, as a contribution to the “controversy over intersubjectivity” that arose in phenomenological circles in interwar Germany, and in which Arendt’s theological teacher, Rudolf Bultmann, also participated. Likewise, it can be read as an implicit criticism of Heidegger’s notion of guilt. From this vantage point, I argue that Arendt’s thinking on forgiveness and guilt developed as part of an ongoing confrontation with Heidegger’s vision of intersubjectivity and guilt—not merely as an outright repudiation, but rather as a critical-transformative appropriation. Furthermore, in contrast to the near-exclusive focus on The Human Condition (1958) in the scholarly literature, I establish that Arendt contemplated forgiveness in many other texts, both before and after 1958, and continuously revised her account. In fact, Arendt was initially altogether opposed to forgiveness. Her turn to approving forgiveness was connected to a different view as to what forgiveness is; essentially, it was contingent upon a political-intersubjective reinterpretation: namely, that she began to see forgiveness and the correlating notion of guilt as genuinely political-intersubjective phenomena.