Psychological assessment is the systematic process by which psychologists evaluate characteristics of people (Weiner, 2010). Characteristics may include personality traits, intelligence, neuropsychological functions, psychiatric symptoms or disorders, behaviors and their contingencies, attitudes and beliefs, learning disabilities, academic achievement, school readiness, adaptation to medical illness and disabilities, appropriateness for surgery or organ donation, adaptive and social functioning, coping skills, quality of life, fitness for duty, criminality, and competency to stand trial, among others. It may extend beyond individual characteristics to the assessment of parent–child or couple interactions, family functioning, or group and organizational factors. The outcome of the assessment involves a report that can be instrumental in securing services for patients, whether through educational or other social service systems.

Psychological assessment usually involves the integration of multiple sources of data for characterizing people, including interviews, behavioral observations, administration of standardized assessments, collateral reports, and historical documents. A key component of most psychological assessment is the use of reliable, standardized, norm-referenced and valid psychological tests or measures to gather data. These tests often have norms by which psychologists can compare an individual’s performance with those of others (e.g., age groups, psychiatric populations). Depending on the nature of the assessment, psychologists rely on one or more methods or tests to make their determinations. The use of multiple tests within a single assessment is called a “battery.” A “common battery” refers to the use of the same core set of tests across individuals based on contemporary research and practice findings within an area of psychological assessment. Common batteries help standardize the assessment and measure change in testing performance over time. Psychologists often supplement common batteries with other measures to further refine and individualize the assessment process. There are many different cognitive and psychological assessments, and specific instruments that are suitable to evaluate infants/toddler, preschoolers, school-age children and adolescents, adults, and geriatric populations.