The DSM-5 Alternative Model for Personality Disorders (AMPD) characterizes borderline personality disorder (BPD) in part as a constellation of maladaptive personality trait facets including emotional lability, anxiousness, separation insecurity, depressivity, impulsivity, risk-taking, and hostility. Previous studies have supported the construct validity of AMPD-BPD; however, research examining its predictive validity in relation to theoretically and clinically relevant constructs remains needed. The present study investigates the longitudinal relationships between AMPD-BPD and general distress, rumination, and suicidal ideation, as well as adaptive and maladaptive coping targeted in Dialectical Behavior Therapy (DBT) in a sample of participants with elevated BPD symptomology. We also examined if dysfunctional coping skill use at 9-month follow-up explained the relationship between baseline BPD traits and outcomes at 1-year. There were significant correlations between baseline trait BPD with dysfunctional coping skill use at 9-month follow-up and psychological distress and rumination at 1-year follow-up. Dysfunctional skill use exhibited a significant indirect effect in the association between trait BPD and rumination after 1 year. The findings of this study support the construct validity of AMPD-BPD that can inform treatment and research.