The paper focuses on the motif of hope, which plays an important role in Immanuel Kant’s practical philosophy. Hope builds a bridge between ethics and the philosophy of religion, and it does so as part of the highest good. I examine the notion of hope in Kant’s thought in three steps, based on three texts: Critique of Pure Reason (Canon of Pure Reason), Critique of Practical Reason (Postulates of Pure Practical Reason; Ethico-Theology), and Religion within the Boundaries of Mere Reason (Theory of Radical Evil in Human Nature). I provide arguments to show that, for Kant, hope is a necessary motive. Hope is understood as an attitude of reason, rather than as an emotion. I further demonstrate that in the concept of hope, the desire for happiness intersects with the desire to live well morally. The function of hope, in the context of a lifetime of moral practice, is to help remove obstacles to leading a moral life. Hope is not needed to know what to do. Hope is necessary as a component of the meaningfulness of the whole. The impossibility or loss of hope for the ultimate meaning, as including the achievement of one’s own bliss, would make the lifelong pursuit of morality impossible. Finally, hope turns out to be necessary as a response to the thesis of radical evil in human nature.