This article has two objectives: one is to distinguish and explicate four concepts of solidarity which are found in the writings of Hannah Arendt; the other is to show how Arendt's respect for facts and suspicion of sentiment publicly displayed are justified. The first concept of solidarity is exclusive solidarity. It is limited to those who are suffering from exploitation or oppression. The second conception of solidarity is inclusive: it includes those who suffer but can also accommodate those who make common cause with them. This is the only kind of solidarity that Arendt specifically analyzes. A third concept of solidarity is universal: its proximate constituent parts are the different “peoples” who collectively make up humankind. Finally, there is natural solidarity. This variety of solidarity, the author argues, is conceptually inadequate and confused. In the development and articulation of each of these four concepts, some attention is given to the relative contributions of emotion and cognition in determining one's understanding of solidarity.