Cyber dating abuse (CDA), defined as threatening, monitoring, and abusing a dating partner via technology (e.g., smartphones, social media), is perpetrated by 44%-55% of college students annually. Borderline personality disorder (BPD) traits recently emerged as a CDA risk factor, but mechanisms underlying this association remain uninvestigated. Based on prior research and theory, we hypothesized that emotion dysregulation (ED; i.e., poor ability to regulate emotions) would explain the association between BPD traits and CDA perpetration. Cross-sectional, self-report data were collected from 254 undergraduate students (55.9% women). Statistically accounting for age and sex, results supported our hypothesis and revealed a significant indirect association between BPD traits and CDA perpetration that was fully explained by ED (B =.15, SE =.09; 95% CI: [.005,.391]), F(4, 249) = 5.42, p <.001. Results align with emerging data that support ED as an important partner abuse risk factor, particularly among those with BPD traits. These preliminary findings may inform CDA conceptualizations, thereby expanding broader partner abuse theories.