The Personality Diagnostic Questionnaire-4th Edition (PDQ-4) is a 100 item, self-administered, true/false questionnaire that yields personality diagnoses consistent with the DSM-IV diagnostic criteria for the axis II disorders. It takes approximately 10-20 minutes to complete. It is widely used in clinical practice and in research projects throughout the U.S.A and other part of the world and has been translated in several different languages.

Patients or participants are given 100 descriptions of abnormal behaviors (eg "I am often on guard of being taken advantage of"). They are asked to indicate whether each description is "generally true" or "generally false" of them. If the patient indicates a sufficient number of abnormal behaviors that are related to specific personality disorder are True for them, an additional series of questions are asked in the Clinical Significance Scale (CSS) section of the test. In the CSS section first asks the patient to review his/her responses to the series of questions that are indicative of a personality disorder. At this time, responses maybe "deselected". Then an additional series of questions are asked concerning: the duration of the behavioral traits, in what situations they occur, if the traits have caused problems for the patient, if the traits are concurrent with axis I problems, and if the patient is bothered by the behaviors. This information is sufficient to make the diagnosis of the presence of a personality disorder. Diagnoses should always be confirmed by a clinical interview.