Few psychological concepts evoke simultaneously as much fascination and misunderstanding as psychopathic personality, or psychopathy. Typically, individuals with psychopathy are misconceived as fundamentally different from the rest of humanity and as inalterably dangerous. Popular portrayals of "psychopaths" are diverse and conflicting, ranging from uncommonly impulsive and violent criminal offenders to corporate figures who callously and skillfully manuever their way to the highest rungs of the social ladder. Despite this diversity of perspectives, a single well-validated measure of psychopathy, the Psychopathy Checklist-Revised (PCL-R; Hare, 1991; 2003), has come to dominate clinical and legal practice over recent years. The items of the PCL-R cover two basic content domains-an interpersonal-affective domain that encompasses core traits such as callousness and manipulativeness and an antisocial domain that entails disinhibition and chronic antisocial behavior. In most Western countries, the PCL-R and its derivatives are routinely applied to inform legal decisions about criminal offenders that hinge upon issues of dangerousness and treatability. In fact, clinicians in many cases choose the PCL-R over other, purpose-built risk-assessment tools to inform their opinions about what sentence offenders should receive, whether they should be indefinitely incarcerated as a "dangerous offender" or "sexually violent predator," or whether they should be transferred from juvenile to adult court. The PCL-R has played an extraordinarily generative role in research and practice over the past three decades-so much so, that concerns have been raised that the measure has become equated in many minds with the psychopathy construct itself (Skeem & Cooke 2010a). Equating a measure with a construct may impede scientific progress because it disregards the basic principle that measures always imperfectly operationalize constructs and that our understanding of a construct is ever-evolving (Cronbach & Meehl, 1955). In virtually any domain, the construct-validation process is an incremental one that entails shifts in conceptualization and measurement at successive points in the process of clarifying the nature and boundaries of a hypothetical entity. Despite the predominance of the PCL-R measurement model in recent years, vigorous scientific debates have continued regarding what psychopathy is and what it is not. Should adaptive, positive-adjustment features (on one hand) and criminal and antisocial behaviors (on the other) be considered essential features of the construct? Are anxious and emotionally reactive people that are identified as psychopaths by the PCL-R and other measures truly psychopathic? More fundamentally, is psychopathy a unitary entity (i.e., a global syndrome with a discrete underlying cause), or is it rather a configuration of several distinguishable, but intersecting trait dimensions? Although these and other controversies remain unresolved, theory and research on the PCL-R and alternative measures have begun to clarify the scope and boundaries of the psychopathy construct. In the current comprehensive review, we provide an integrative descriptive framework-the triarchic model-to help the reader make sense of differing conceptualizations. The essence of this model is that alternative perspectives on psychopathy emphasize, to varying degrees, three distinct observable (phenotypic) characteristics: boldness (or fearless dominance), meanness, and disinhibition. The triarchic framework is helpful for clarifying and reconciling seemingly disparate historical conceptions, modern operationalizations, and contemporary research programs on psychopathy. Our review addresses what psychopathy is, whether variants or subtypes exist (i.e., primary and secondary, unsuccessful and successful), the sorts of causal influences that contribute to psychopathy, how early in development psychopathy can validly be identified, and how psychopathy relates to future criminal behavior and treatment outcomes. Despite controversies and nuances inherent in each of these topics, the current state of scientific knowledge bears clear implications for public policy. Policy domains range from whether psychopathic individuals should be held responsible for their criminal actions to whether employers should screen job candidates for tendencies toward psychopathy. In many cases, the findings we review converge to challenge common assumptions that underpin modern applications of psychopathy measures and to call for cautions in their use. For example, contemporary measures of psychopathy, including the PCL-R, appear to evidence no special powers in predicting violence or other crime. Instead, they are about as predictive as purpose-built violence-risk-assessment tools, perhaps because they assess many of the same risk factors as those broader-band tools. Specifically, the PCL-R and other psychopathy measures derive most of their predictive utility from their "Factor 2" assessment of antisocial and disinhibitory tendencies; the "Factor 1" component of such measures, reflecting interpersonal and affective features more specific to psychopathy, play at best a small predictive role. Similarly, current measures of psychopathy do not appear to moderate the effects of treatment on violent and other criminal behavior. That is, an increasing number of studies suggest that psychopathic individuals are not uniquely "hopeless" cases who should be disqualified from treatment, but instead are general "high-risk" cases who need to be targeted for intensive treatment to maximize public safety. Misunderstandings about the criminal propensities and treatability of individuals achieving high scores on measures like the PCL-R have been perpetuated by professionals who interpret such high scores in a stereotypic manner, without considering nuances or issues of heterogeneity. A key message of our review is that classical psychopathy, whether measured by the PCL-R or other measures, is not monolithic; instead, it represents a constellation of multiple traits that may include, in varying degrees, the phenotypic domains of boldness, meanness, and disinhibition. Measures such as the PCL-R that do not directly assess features of low anxiety, fearlessness, or boldness more broadly tend to identify heterogeneous subgroups of individuals as psychopathic. As a consequence, efforts to apply one-size-fits-all public policies to psychopathic individuals may be doomed to failure. In aggregrate, these conclusions may help to shed light on what psychopathy is, and what it is not, and to guide policy interventions directed toward improved public health and public safety.