Psychopathy has traditionally been characterised as a disorder primarily of personality (particularly affective deficits) and, to a lesser extent, behaviour. Although often used interchangeably, the diagnostic constructs of psychopathy, antisocial personality disorder, and dissocial personality disorder are distinct. In this article, the relevant historical and contemporary literature concerning psychopathy is briefly reviewed. The diagnostic criteria for psychopathy, antisocial personality disorder, and dissocial personality disorder are compared. Consideration is given to the assessment, prevalence, and implications of psychopathy for violence risk and treatment efficacy. The DSM-IV-TR criteria for antisocial personality disorder, in particular, are largely behaviourally based. The ICD criteria for dissocial personality disorder, while paying more attention to affective deficits, also do not represent the broad personality and behavioural components of psychopathy.