This study assessed aspects of the construct validity of the Multidimensional Personality Questionnaire (MPQ), a measure of normal personality characteristics, in a clinically relevant sample through joint factor analyses of primary and second-order scales of the MPQ and the Minnesota Multiphasic Personality Inventory (MMPI). A subsample from the Washington University Twin Study of Psychopathology was analyzed. The MPQ's primary scales and higher order factors were found to have meaningful associations with MMPI scales that served as construct markers. The MPQ taps constructs related to, although not redundant with, those measured by the MMPI. Additionally, the MPQ provides a Constraint measure that is relevant to the study of psychopathy and not represented among the MMPI clinical scales. The potential utility of the MPQ in clinical settings as an adjunct to traditional assessment instruments such as the MMPI is discussed.