The experience of rejection or abandonment in Borderline Personality Disorder (BPD) can lead to profound changes in affect. Yet, the intensity, duration, and type of mood changes that occur in response to rejection remain unclear. This study examined the effect of ostracism upon mood in 30 outpatient youth diagnosed with BPD and 22 healthy community control participants (aged 15?24). Cyberball, a virtual balltoss game, was used to simulate ostracism and 13 mood states were recorded before, immediately after, and 15 minutes after the game. The results showed that while ostracism induced changes in anger, rejection, surprise, suspicion, and joy, there were no differences in the pattern of emotional responding and regulation between the two groups. The BPD group consistently rated their mood as more intense across all 13 mood states and across time compared with the control group. These findings suggest that, compared to healthy individuals, those youth with BPD experience negative emotions as more intense and that in mild cases of interpersonal rejection, their emotional responding and regulation are similar to their healthy peers.