A significant area of proficiency for many clinical psychologists is analysis, assessment and diagnosis, around 91% of psychologists apply the core clinical practice. There is little agreement on the scale to which the mental disorders are universal or differ on their core definitions to the extent. This clash continues due to the lack of biological markers, predictable measurement and the lack of a high standard for recommending most psychiatric conditions. Diagnosis and prognosis is the identification of diseases by the examination of signs and indication, the function, the expected duration, and a description of the initiation and development of the disease, like intermittent crisis, progressive abatement, or sudden, unpredictable crisis. Methods involved in psychiatry comprise of both old traditional and advanced methods for assessment. Under present topic from simple physical examination to advanced Neuro imaging techniques can be highlighted.