This chapter focuses on the practical issues to consider when making personality disorder classifications, as defined by DSM, within forensic settings. Classification of personality disorder within DSM-IV-TR is based on identification of a number of traits presented by the individual. A number of instruments have been developed to assess and classify Personality Disorder, with a range of new instruments being developed specifically to assist in DSM classification. While there is extensive information about personality disorder, much less information is available about personality disorder and its assessment in forensic populations. A number of studies have examined the use of personality disorder classifications in forensic populations. It is not sufficient to only identify traits within a single setting; adequate information must be available to assess early conduct disorder and the appearance of traits in late adolescence and early adulthood. Motivational factors related to the completion of the assessment should also be considered.