Its controversial past notwithstanding, psychopathy has emerged as one of the most important clinical constructs in the criminal justice and mental health systems. One reason for the surge in theoretical and applied interest in the disorder is the development and widespread adoption of reliable and valid methods for its measurement. The Hare PCL-R provides researchers and clinicians with a common metric for the assessment of psychopathy, and has led to a surge in replicable and meaningful findings relevant to the issue of risk for recidivism and violence, among other things. Most of the research thus far has been based on North American samples of offenders and forensic psychiatric patients. We summarize this research and compare it with findings from several other countries, including England and Sweden. We conclude that the ability of the PCL-R to predict recidivism, violence, and treatment outcome has considerable cross-cultural generalizability, and that the PCL-R and its derivatives play a major role in the understanding and prediction of crime and violence.