The OMNI Personality Inventory (OMNI) is a self-report questionnaire designed for use with adolescents and adults between 18 and 74 years of age. The questionnaire is not based on a particular theory, consistent with current trends in test development, according to the author. An abbreviated form of the OMNI, the OMNI-IV Personality Disorder Inventory (OMNI-IV), consists of items focused exclusively on the identification of personality disorders as defined by the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed., text revision; American Psychiatric Association, 2001). The inventories were developed in an attempt to merge academic and clinical approaches to understanding characteristics in adolescents and adults and may be used in clinical and research settings. Specifically, assessment of both "normal" personality characteristics and "abnormal" traits represents a major goal in the development of the OMNI. This article discusses the following: (1) item format, scoring and interpretation of OMNI and OMNI-IV; and (2) the tests' technical adequacy. This article also offers a review of OMNI. (Contains 1 table.)