It is argued that an existential-ontological framework provides a more in-depth understanding of an individual’s experiencing of psychosis than the dominant biomedical models of psychopathology. Psychosis experience (PE) exists on a spectrum with “normal” experience instead of being defined as a discrete disease entity; and on the ontological ground of a simultaneous, reciprocal relationship between the organism and environment. First, I discuss the ontological-ontic dimensions of lived experience. I will argue that the ontological issues of Being and the nature of human existence are implicitly present in, and intertwined with, the ontic activities of psychology and psychotherapy. Second, the existential-ontological framework developed by Hersch (2015) is utilized to explain six key aspects of human experience that can be applied in, for example, the ontic task of psychotherapy that seeks to understand the lived worlds of persons with PE. While Hersch’s systematic approach owes much to Heidegger, Sartre, and Merleau-Ponty, I will also discuss these dimensions from the viewpoints of persons with PE together with other perspectives from person-centered, cognitive–behavioral and existential psychotherapies, and from neuropsychiatry.