While the concept of psychopathy evolved into a formal clinical disorder over a century ago, the causes of the disorder remain unclear and only recently have psychometric measures been formulated to measure psychopathy as a construct. This article begins with a review of the theoretical literature, describing how arousal theory, neurobiological theory, and social learning theory have explained psychopathic personalities. Researchers have also hypothesized that psychopaths have moral-reasoning deficits, fear and anxiety deficits, and selective attention deficits. In addition to the psychological, biological, and neurological explanations for psychopathy, researchers have identified developmental pathways to psychopathy, such as Saltaris’s (2002) assertion that psychopathy in adulthood could be attributed to aggressive and antisocial behavior during childhood. Following a consideration of various developmental pathways to psychopathy, the author turns to a discussion of the measurement of psychopathy, focusing specifically on Hare’s Psychopathy Checklist-Revised (PCL-R) which measures the core personality characteristics of psychopathy as well as anti-social behaviors. The PCL-R was devised as a way of measuring psychopathy as a clinical construct but it has also demonstrated effectiveness at predicting violent and sexual offending risk and recidivism among offenders and is therefore used widely for offender risk assessment. Finally, treatment and intervention approaches for psychopaths are examined, tracing the development of treatment options from those focusing on anger management and the development of social skills to more recent treatments that focus on behavioral approaches, such as the Psychopathy Treatment Program that offers a strategy for behavioral self-management. Despite the research, theories, and treatments addressing psychopathy, this disorder is still not fully understood but is best thought of as a multi-dimensional disorder involving an interaction between neurobiological, psychological, social, and environmental factors. Implications for practice and policy are discussed and researchers are urged to examine the emergence of the “white-collar” psychopath. Tables, notes, references