Personality assessment, the measurement of personal characteristics. Assessment is an end result of gathering information intended to advance psychological theory and research and to increase the probability that wise decisions will be made in applied settings (e.g., in selecting the most promising people from a group of job applicants). The approach taken by the specialist in personality assessment is based on the assumption that much of the observable variability in behaviour from one person to another results from differences in the extent to which individuals possess particular underlying personal characteristics (traits). The assessment specialist seeks to define these traits, to measure them objectively, and to relate them to socially significant aspects of behaviour.