In addition to suffering from the severe psychiatric symptoms of chronic mental illness (CMI), people with this type of disorder suffer from a variety of secondary disabilities and face societal obstacles that interfere with their ability to maximize their personal, social, and vocational potentials. Following the deinstitutionalization of long-term psychiatric patients in recent decades, many different understandings of the etiology, treatment, and management of CMI have evolved, including those derived from the biological, vulnerability, cognitive, case management, rehabilitation, and psychoeducational models. Because psychologists are trained in a wide range of psychological theories and a broad repertoire of applications, they have unique contributions to make within each model, particularly, as discussed here, to prevent, treat, and manage CMI through research, assessment, and intervention.