Psychological Evaluations assess whether an individual appears to have psychological problems. In particular, psychologists assess whether the individual has the symptoms of any specific psychological diagnoses. An evaluation may also describe or explain general psychological adjustment problems being presented by an individual, in an effort to understand the individual’s behavior. Identifying specific problems is a necessary stop in the development of a treatment plan. The evaluation determines what time of treatment is most likely to be beneficial. Diagnostic evaluations can be informal assessments made during the initial interview with a client at the beginning of psychotherapy, and may include one or two psychological tests. A comprehensive psychological evaluation may take several hours, or even several days, depending on the problems being assessed, and the reason for the assessment. Comprehensive evaluations often include several psychological testing instruments.