Despite evidence for the interrelations of interpersonal and emotional functioning within borderline personality disorder (BPD), little research has examined the impact of socially-oriented emotion regulation strategies among individuals with BPD symptoms. This study examined the impact of one such regulation strategy, social comparison (SC; upward vs. downward), on changes in negative emotions and cognitions following exposure to either a social threat or neutral condition of an online social interaction task among young women with a range of BPD symptoms. We hypothesized that BPD symptoms would be related to (a) greater increases in negative emotions and cognitions following upward SC among participants in both conditions, (b) greater increases in negative emotions and cognitions following downward SC among participants in the social threat condition, and (c) greater decreases in negative emotions and cognitions following downward SC among participants in the neutral condition. Providing partial support for hypotheses, results suggested that the cognitive consequences of downward SC may vary depending on the presence or absence of social threat. Specifically, results revealed a significant association between BPD symptoms and decreases in perceived threats to self-esteem and control following downward SC, but only among women in the neutral condition of the social interaction task. Conversely, although downward SC in the absence of social threat may be effective for regulating some negative cognitions, it may paradoxically increase negative affect among women with heightened BPD symptoms. Results highlight the need for further research examining the emotional and cognitive impact of social comparison among women with BPD symptoms.