Going beyond the scope of psychiatric diagnoses, this study introduces the concept of human vulnerability as a means of linking the phenomenological approach—focusing on the patient’s experience—with psychotherapeutic treatment. To this end, it applies Karl Jaspers’ concept of “limit situation” to the existential vulnerability in the manifestation of mental illness and the ontological vulnerability in schizophrenia. From a psychological or empathic standpoint, vulnerability, as experienced in different cases of mental illness, refers to the condition of being confronted with disturbing meaningful (...) social encounters with others. In these social encounters, existential meanings acquire disturbing qualities for a person’s integrity, giving rise to various psychopathological phenomena. This study incorporates the practice of psychotherapy and empirical research to suggest that the experience of vulnerability is crucial not only in understanding the manifestation of mental illness but also a key element of phenomenological psychotherapeutic treatment, and it uses schizophrenia as an example. (shrink)