Dr. Hare has spent over 35 years researching psychopathy and is the developer of the Hare Psychopathy Checklist-Revised (PCL-R), and a co-author of its derivatives, the Psychopathy Checklist: Screening Version (PCL:SV), the P-Scan, the Psychopathy Checklist: Youth Version (PCL:YV), and the Antisocial Process Screening Device (APSD). He is also a co-author of the Guidelines for a Psychopathy Treatment Program. The Hare Psychopathy Checklist-Revised, with demonstrated reliability and validity, is rapidly being adopted worldwide as the standard instrument for researchers and clinicians. The PCL-R and PCL:SV are strong predictors of recidivism, violence and response to therapeutic intervention. They play an important role in most recent risk-for-violence instruments. The PCL-R was reviewed in Buros Mental Measurements Yearbook (1995), as being the "state of the art" both clinically and in research use. In 2005, the Buros Mental Measurements Yearbook review listed the PCL-R as "a reliable and effective instrument for the measurement of psychopathy and is considered the 'gold standard' for measurement of psychopathy.