The concept of emotion dysregulation has been integrated into theory and treatment for borderline personality disorder (BPD), despite limited empirical support. Expanding upon existing research on the relationship between emotion dysregulation and BPD, the present study utilized a multimodal approach to the assessment of emotion dysregulation (including two behavioral measures of the willingness to tolerate emotional distress, and a self-report measure of emotion dysregulation broadly defined) to examine the relationship between emotion dysregulation and BPD among inner-city substance users in residential treatment (n=76, with 25 meeting criteria for BPD). Results provide laboratory-based evidence for heightened emotion dysregulation in BPD, extending extant research on BPD to underserved clinical populations. Specifically, the presence of a BPD diagnosis among a sample of inner-city inpatient substance users was associated with both higher scores on the self-report measure of emotion dysregulation and less willingness to tolerate emotional distress on the behavioral measures of emotion dysregulation. Moreover, both self-report and behavioral measures of emotion dysregulation accounted for unique variance in BPD status, suggesting the importance of utilizing comprehensive assessments of emotion dysregulation within studies of BPD. Findings suggest the need to further explore the role of emotion dysregulation in the development and maintenance of BPD among inner-city substance users in residential treatment.