The triarchic model of psychopathy (Patrick, Fowles, & Krueger, in press) conceptualizes this intriguing disorder in terms of three distinct elemental phenotypes: disinhibition, reflecting tendencies toward deficient behavioral control and externalizing psychopathology; meanness, reflecting deliberate cruelty and agentic exploitation of others; and boldness, reflecting resilience to life stress, calmness in the face of threat, and social dominance. The predominant instrument for assessing criminal psychopathy, Hare’s (1991, 2003) Psychopathy Checklist-Revised (PCL-R), appears to tap the disinhibition and meanness facets of psychopathy directly and substantially, but captures boldness only indirectly and to a modest degree. Given its reliance on antisocially deviant indicators, the PCL-R is also ill-suited to investigation of noncriminal psychopathy in community settings. Thus, the primary aim of the present study was to evaluate the construct validity and neurobiological correlates of a newly-developed interview measure of the phenotypic boldness construct. Relationships between the Boldness Interview (BI) and multi-modal measures of psychopathy, externalizing psychopathology, and personality traits with theoretical or empirical links to the boldness construct were investigated in a sample of incarcerated adult males. The present study also investigated relationships between the BI measure and emotional modulation of the startle blink reflex – a well-validated physiological measure of fear reactivity that has previously been linked to the interpersonal-affective features of PCL-R psychopathy – in a picture-viewing paradigm. Results strongly supported the construct validity of the BI. Consistent with theory and prediction, BI total scores were: substantially and positively related to the PCL-R Interpersonal facet, the fearless dominance factor of the self-report Psychopathic Personality Inventory (Lilienfeld & Andrews, 1996), and self-reported narcissism, thrill-seeking, and dominance; negatively related to self-report measures of harm avoidance, trait anxiety, fear, and internalizing symptoms; and largely unrelated to externalizing psychopathology. Total scores on the BI were also related to reduced startle amplitude during aversive pictures in the picture-viewing paradigm. These results are discussed in terms of their implications for the assessment and conceptualization of psychopathy (particularly non-criminal psychopathy) as well as the neurobiological underpinnings of the disorder.