OBJECTIVE Borderline personality disorder (BPD) is a common mental health condition in psychiatric settings. The current study examined the overlap between the operationalization of BPD listed in Section II (Diagnostic Criteria and Codes) and the alternative, dimensional personality trait-based operationalization listed in Section III (Emerging Measures and Models) of the current Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Moreover, the unique contributions of specific personality traits for indexing the traditional BPD operationalization were also evaluated, including conceptually relevant traits not originally proposed for Section III BPD. METHODS Participants were 145 consecutive patients from a psychiatric unit in a hospital in the USA. These individuals completed a series of questionnaires that index both traditional (DSM-IV/DSM-5 Section II) and alternative (DSM-5 Section III personality traits) diagnostic criteria for BPD. RESULTS Structural equation modeling results revealed that latent constructs representing the Section II and Section III operationalizations of BPD, respectively, overlapped substantially (r = 0.86, p < 0.001). Hierarchical latent regression models indicated that at least five of the seven traits proposed to define Section III BPD uniquely accounted for variance (69%) in a latent Section II BPD variable. Finally, at least one other conceptually relevant trait (Perceptual Dysregulation) augmented the prediction of latent BPD scores. CONCLUSIONS The proposed personality traits for Section III BPD are clearly aligned with traditional conceptualizations of this important personality disorder construct. At least five of the seven dimensional traits proposed to define Section III contributed uniquely to the characterization of Section II BPD, and these traits can be augmented by Perceptual Dysregulation. If replicated in other settings, these findings might warrant some modification to the operationalization of DSM-5 Section III BPD.