Over the past 2 decades there has been a dramatic shift in understanding of personality disorders, such as borderline personality disorder (BPD). What was historically viewed as an entrenched pattern of antagonistic, interpersonally dependent, and uncorrectable conduct is now seen as the outcome of complex-yet modifiable-developmental processes. The borderline label, which once inspired such harsh opprobrium in clinical communities that early diagnosis was considered taboo, is now increasingly applied to adolescents who are receiving effective treatment and desisting from a borderline trajectory. Research examining the developmental origins and early manifestations of BPD is increasing rapidly, making it an appropriate time to take stock of current developmental research and articulate an agenda for the future. We identify 4 challenges that continue to impede innovative research on borderline personality development: (a) inadequate attention to continuity and discontinuity across development, (b) medical and diagnostic systems that localize personality pathology within the individual, (c) the lingering belief that biological research is antithetical to contextual/interpersonal understandings of psychopathology (and vice versa), and (d) reluctance to reach across disciplinary and developmental boundaries to identify creative paradigms and foster innovative discovery. In order to overcome these challenges, we propose an approach to future research on adolescent borderline pathology that integrates developmental psychopathology, social and affective neuroscience, and personality theory perspectives. This intersection- the developmental neuroscience of personality pathology-offers theoretical and methodological advantages over disciplinary isolation and is fertile ground for generating novel hypotheses on the development and prevention of BPD.