Mindfulness is a core component of dialectical behavior therapy (DBT), a widely utilized treatment for borderline personality disorder (BPD); however, the import of mindfulness in treating BPD has yet to be demonstrated, and the relationship of mindfulness to BPD constructs is unclear. The current study utilized structural equation modeling to examine the relations of mindfulness with BPD features and the underlying constructs of interpersonal problem-solving effectiveness, impulsivity, emotion regulation strategies, and neuroticism in 342 young adults. Mindfulness was significantly related to effectiveness in interpersonal problem-solving, impulsivity and passivity in emotion regulation, and borderline features. Furthermore, mindfulness continued to predict borderline features when controlling for interpersonal problem-solving and impulsive/passive emotion-regulation strategies, as well as when controlling for neuroticism. It is concluded that difficulties with mindfulness may represent a core feature of BPD and that improvement in mindfulness may be a key component of treatment efficacy with BPD. It is recommended that the unique contribution of mindfulness be investigated in future treatment-outcome research.