Psychological tests can evaluate ability, such as intelligence, aptitude skills, and achievement; deficits after stroke or head injury; and personality, such as traits, attitudes, rigidity, and values.

A psychological assessment typically includes an interview, observations, and the administration of various intellectual tests, personality tests, parenting tests, etc. The procedures used vary based on the referral need. Psychologists use instruments that are designed to identify strengths and weaknesses in multiple areas within an individual. Tests may be designed to identify a learning disorder, attention and impulsivity problems, mood difficulties, and personality style.

An assessment does not necessarily have to be in regards to a disorder, but may be used to identify if an individual is a good fit for an organization, or how they will work within a team. Often times, psychological assessment is used to understand a person's difficulty within a specific role in his or her life. For example, if a relatively capable child is struggling in school, the assessment can identify which area of weakness is preventing the child from maximizing his or her potential. The child may have a weakness in attention, impulsivity, struggling with depression, or have a a specific learning difficulty. ​​​

Psychologists are also in a unique position to assist in criminal matters. Intelligence and personality testing may assist in understanding ability to waive Miranda Rights as it relates to understanding, comprehension, and personality variables related to voluntary waiver. Evaluations are often requested at sentencing hearings as well.​​​

After an assessment is completed, recommendations are made to offer strategies to maximize one's potential.