The triarchic model posits that psychopathy is a combination of phenotypes related to boldness, meanness, and disinhibition. We examined how each of these phenotypes of psychopathy related to past violence and antisocial behavior and to behavior within the prison. The sample consisted of men ( n = 108) with a history of serious offending and a diagnosis of personality disorder at the point of admission to a prison serving as a therapeutic community. We took four indices of violence and antisocial behavior, (a) self-report of lifetime proactive and reaction aggression, (b) criminal convictions prior to admission to the prison, (c) exclusion from the prison within 12 months due to rule breaking, and (d) behavior within the first 12 months of admission to the unit. The constructs of the triarchic model, as assessed by the triarchic psychopathy measure (TriPM), were strong predictors of self-reported aggression, with disinhibition being related to both proactive and reactive aggression, whereas boldness was related to proactive aggression alone. Past criminal convictions were also associated with disinhibition, except for convictions for violent behavior. Both meanness and disinhibition were predictive of exclusion from the prison within 12 months for rule-breaking behavior and of aggressive behavior within the prison. The triarchic model of psychopathy is associated with past antisocial behavior and is predictive of antisocial behaviors within the prison, and the different constructs of the triarchic model are associated with different manifestations of antisocial behavior. The TriPM holds great promise for improved assessment and enhanced understanding of psychopathic personality within institutions and can facilitate offender management via improved phenotypic analysis of boldness, meanness, and disinhibition.