Psychological testing is one of the means to aid in making diagnosis, treatment plan, response to treatment, placement assignment, etc. Usually, clinical interview and historical information are sufficient for the aforementioned purposes. However, there are situations that psychological testing is necessary to provide thorough information for various purposes. Psychological testing uses standardized testing instrument to assess various areas of a person’s mental condition, including intelligent functioning, academic achievement, neuro-psychological conditions, occupation interest, personality, etc. In many cases, one or combination of these tests will be able to provide enough information in question. In other cases, a full battery of tests is required to reach the goal of a more complex evaluation. The selection, administration, scoring, and interpretation throughout a psychological testing are performed by a well-trained and experienced psychologist or counselor.