Psychedelics have shown promise as a treatment for depression. Although there is some debate, a popular view is that psychedelics produce their benefits in an experience-dependent manner. This is the view that a depressed person gets better, inter alia, because of the experience she has had on psychedelics. Among the various questions that treatment for depression with psychedelics raise, one of the most important is: By what mechanism do these drugs reduce symptoms? If the experience-dependent view is correct, the answer, (...) at least on the personal level of explanation, lies in the phenomenology. In this paper, borrowing mainly from Ratcliffe’s account of depression, I offer such an answer. I argue that psychedelic experiences involve a surge of existential feelings, which can revise the depressed person’s diminished sense of possibility and restore their ability to be affected by the world. I explain how this occurs via a change in the sense of reality linked to the subjective effects of psychedelics. This, I suggest, is the personal level mechanism or process behind psychedelic-assisted psychotherapy for depression. (shrink)