ObjectiveThis study investigated impulsivity-related personality traits using the Revised NEO Personality Inventory (NEO PI-R) in women diagnosed with co-occurring bulmia nervosa and borderline personality disorder (BN-BPD), borderline personality disorder (BPD no-BN), or major depressive disorder (MDD-only). MethodThe sample included 672 adult female admissions to a psychiatric day hospital treatment program. The NEO PI-R facets of impulsiveness (N5), excitement-seeking (E5), self-discipline (C5), and deliberation (C6) provided a proxy assessment of impulsivity-related traits tapping negative urgency, sensation-seeking, lack of perseverance, and lack of premeditation/planning. ResultsAfter adjusting for age, BN-BPD displayed significantly higher levels of negative urgency and lack of premeditation than BPD without co-occurring BN. Women with BN-BPD also had significantly higher levels of impulsivity traits than MDD across domains, except for lack of perseverance. DiscussionImpulsivity-related traits of negative urgency and lack of premeditation significantly differentiated women with versus without co-occurring BN among women with borderline personality disorder. Lower levels of impulsivity-related traits in women with MDD indicated that effects were not simply attributable to any form of psychopathology. Of the impulsivity traits, negative urgency demonstrated the strongest effect, providing further evidence of the important relationship between negative urgency and the expression of bulimic symptomology. (c) 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:1093-1096)