Although anecdotal case accounts suggest that evidence concerning Antisocial Personality Disorder (APD), sociopathy and psychopathy is frequently introduced by the prosecution in capital murder trials, to date there has been no systematic research to determine the actual prevalence, role, or perceived impact of such evidence in these cases. Survey data collected from attendees at a national capital mitigation conference (n = 41) indicated that prosecution evidence concerning APD was quite prevalent, with “sociopath” and “psychopath” labels being introduced less frequently. Evidence concerning these disorders, which were assessed primarily via DSM criteria and self-report personality inventories, was most often introduced by the prosecution in the sentencing phase to address a defendant's ostensible risk of future dangerousness and/or to rebut mitigating evidence—although it was also introduced frequently in the guilt/innocence phase of these trials to rebut mental health evidence offered by the defense. Survey respondents believed that evidence concerning APD, sociopathy, and psychopathy had a considerable impact on trial outcomes. Also, although defense objections were common, such evidence was rarely ruled to be inadmissible in these cases. Copyright © 2012 John Wiley & Sons, Ltd.