Interpersonal dysfunction and self-injurious behaviors are core characteristics of borderline personality disorder (BPD) thus, the aim of this dissertation was to investigate the impaired neural processing of (negative) social signals in BPDs, and how this impairment affects the processing of physical pain. Using a combination of behavioral and neuroimaging techniques, the results from this dissertation add an important dimension to the understanding of the underlying neural mechanisms contributing to interpersonal dysfunction in BPD and show that these factors are strongly linked to early life stress. Specifically, the amygdala and temporal poles, key nodes of the social brain, were implicated in dysfunctional processing across these experiments further supporting impairments during emotional processing and an inability to properly integrate social signals by these patients. Additionally, these results help to clarify the mechanisms that may underlie the self-injury, a dangerous characteristic of this patient population.