Theory and research identify emotion dysregulation as one of the primary mechanisms underlying borderline personality disorder (BPD) and related pathology. Yet, despite the extensive research documenting an association between emotion dysregulation and BPD, many questions regarding the precise role of emotion dysregulation in the development and treatment of BPD and its associated difficulties remain unanswered. This paper reviews the extant literature on the role of emotion dysregulation in BPD and its associated difficulties, as well as the treatment of BPD-related pathology, and identifies important next steps for future research in this area. In particular, this review highlights the need for further research examining: (a) the dimensions of emotion dysregulation that are unique to BPD, (b) the role and nature of interpersonal (vs. intrapersonal) emotion regulation in BPD, (c) the role of emotion dysregulation in the physical (vs. mental) health problems associated with BPD, and (d) the role of emotion regulation in efficacious treatments for BPD. Such research has the potential to elucidate the precise emotion regulation deficits that are most relevant (and central) to BPD, the active ingredients and mechanisms of change in current efficacious treatments for BPD, and the most effective and efficient targets for integrative treatments for this population.