Three complementary approaches to understanding psychopathy have been proposed. The five-factor model approach proposes that psychopathy exists as a continuum of disorder, characterised by the traits that comprise normal personality functioning (Ross et al, 2004). A second model of psychopathy, complementary to the FFM approach, is proposed by Blair (1995). He suggests a Violence Inhibition Mechanism (VIM) exists, responsible for aggression inhibition and distinguishing moral from conventional rules. He proposes the VIM is defective in clinical psychopaths – such individuals fail to distinguish moral (e.g. hitting another person) from conventional transgressions (e.g. wearing the opposite sex’s clothes). Activation of the VIM has been shown to be inversely proportional to level of behavioural disturbance in children with psychopathic tendencies, suggesting a continuum of disorder. A third model of psychopathy focuses on aggression: clinical psychopaths exhibit more instrumental and reactive aggression (Cornell et al, 1996). Sub-clinical psychopathy has yet to be linked to aggression; however, the VIM approach predicts that aggression positively correlates with psychopathy, providing support for a model of psychopathy as a continuous disorder. This current study aimed to replicate the proposed relationship between personality and psychopathy (Ross et al, 2004). A further objective was to investigate whether deficits in the moral/conventional would exist in sub-clinical psychopathy, providing support for examining sub-clinical psychopathy through the VIM model. A final aim was to explore whether the aggression model could account for differences in sub-clinical psychopathy. Measures of primary and secondary psychopathy, personality, aggression and the moral/conventional distinction task were administered to 176 participants using a within-subjects design. Supporting the FFM as a measurement tool for sub-clinical psychopathy, primary psychopathy was accounted for by low openness, straightforwardness and tendermindedness and high excitement seeking. Secondary psychopathy was accounted for by low agreeableness, conscientiousness and openness to values, and high angry hostility and excitement seeking. Supporting the aggression model approach to sub-clinical psychopathy, primary psychopathy was accounted for by hostility and physical aggression; secondary psychopathy was accounted for by all four aggression sub-traits. Moral transgressions were judged to be less permissible and more serious than conventional transgressions. Following the removal of the rule prohibiting the transgression, conventional, but not moral transgressions were judged to be more permissible. No distinction was made between transgression types in judgements of seriousness following rule-removal. In opposition to the VIM model, neither psychopathy nor aggression showed a significant relationship with the moral/conventional distinction task. Personality, accounted for a small but significant proportion of variance in the moral/conventional distinction. These unexpected findings may result from problems with the construct validity of the moral/conventional distinction. A better understanding of the moral/conventional distinction is needed before it is employed in further study of psychopathy.