Clinical psychology is an integration of science, theory and clinical knowledge for the purpose of understanding, preventing, and relieving psychologically based distress or dysfunction and to promote subjective well-being and personal development. Central to its practice are psychological assessment and psychotherapy, although clinical psychologists also engage in research, teaching, consultation, forensic testimony, and program development and administration. In many countries, clinical psychology is a regulated mental health profession.
The field is often considered to have begun in 1896 with the opening of the first psychological clinic at the University of Pennsylvania by Lightner Witmer. In the first half of the 20th century, clinical psychology was focused on psychological assessment, with little attention given to treatment. This changed after the 1940s when World War II resulted in the need for a large increase in the number of trained clinicians. Since that time, three main educational models have developed—the Ph.D. Clinical Science model (heavily focused on research), the Ph.D. science-practitioner model (integrating research and practice), and the Psy.D. practitioner-scholar model (focusing on clinical practice). Clinical psychologists are expert in providing psychotherapy, and generally train within four primary theoretical orientations—psychodynamic, humanistic, behavior therapy/ cognitive behavioral, and systems or family therapy.
The earliest recorded approaches assess and treat mental distress were a combination of religious, magical and/or medical perspectives. Early examples of such physicians included Patañjali, Padmasambhava,Rhazes, Avicenna, and Rumi. In the early 19th century, one approach to study mental conditions and behavior was using phrenology, the study of personality by examining the shape of the skull. Other popular treatments at that time included the study of the shape of the face (physiognomy) and Mesmer's treatment for mental conditions using magnets (mesmerism). Spiritualism and Phineas Quimby's "mental healing" were also popular.