While there is considerable evidence for neurobiological and neuropsychological impairments in clinical or incarcerated psychopaths, there is less research examining these domains among nonincarcerated adults with high levels of psychopathic traits (i.e., subclinical psychopaths).The present study examined differences in neuroendocrine and autonomic functioning, affective processing, and self-reported and behavioral aggression in young adult males with high levels of subclinical psychopathy, compared to young adult males with low levels of psychopathic characteristics.Participants completed selfreport questionnaires assessing psychopathic traits, aggression, drug and alcohol use, and other demographic information.They provided salivary cortisol samples before and 25 minutes after participating in a social stressor.Participants completed an affective processing task, during which their skin conductance reactivity was measured.They also engaged in a behavioral aggression task.Contrary to hypotheses, no differences between psychopathic groups were found in basal cortisol levels or cortisol reactivity following a social stressor, skin conductance reactivity while viewing negative pictures, valence ratings while viewing negative pictures, or aggression during a laboratory aggression task.Consistent with hypotheses, males with higher levels of psychopathic traits reported engaging in more physical and verbal aggression compared to the group with lower levels