While the categorical approach (as seen in DSM) tries to establish a comprehensive list of personality types, a dimensional approach looks at key personality traits that vary from person to person. The Five Factor Model of personality has received considerable attention in the research literature. As presented by Paul Costa and Robert McCrae, the Five Factors include openness to experience, conscientiousness, extra-version, agreeableness, and neuroticism (OCEAN). These traits were first identified from factor analytic studies, in which rating scales composed of large lists of emotional words were analyzed to see which words grouped together.

The psychological traits grouped into five different categories. The labels for these categories have varied slightly across different studies, but the OCEAN labels are now widely accepted. Even though there is good evidence that these traits are associated with clinically relevant outcomes, are stable over time, and have some genetic component to them, it is important to note that they are derived from statistical analyses of word lists and not from clinical observations. Therefore, their usefulness in clinical settings may be limited. The Five Factor Model has also been criticized because it is does not provide an actual theory of personality, only a set of empirical findings.