Background: There is little research on how specific borderline personality disorder (BPD) symptoms relate to suicide attempts or suicide and non-suicidal self-injury (NSSI) within adolescent populations, which is important to know given the recent proposal of an NSSI disorder. Even less well known is whether specific BPD symptoms distinguish NSSI from suicide attempts or differentiate single from repeated acts of either suicide or NSSI. Method: Archival, de-identified outpatient clinical charts from 441 ethnically diverse (4.3% Caucasian; 70.9% female) adolescents (mean age = 14.9, SD = 1.61) were reviewed. Data pertaining to NSSI, suicide attempt history, BPD symptoms, and psychiatric diagnoses were obtained from self-report measures and semi-structured interviews administered at intake. Results: MANOVA and logistic regression analyses revealed significant differences across groups, with the BPD symptoms of "confusion about self" and "unstable interpersonal relationships" significantly predicting NSSI and NSSI+Suicide group status. The number of BPD criteria met plus high levels of confusion about self significantly predicted single vs. repeat self-harm group membership. Conclusions: Two BPD symptoms exhibit distinct relationships to NSSI and suicide attempts, but there is not strong variation in their relationship to BPD. Treatment addressing BPD symptoms may be useful to reducing both NSSI and suicide in ethnically diverse adolescents.