Objectives: For a long time, BPD had the reputation of being a chronic illness with a negative prognosis (Paris, 2007) and until recently there were important gaps in our knowledge of the disorder (Skodol et al., 2005). Recent longitudinal studies showed that its course is better than previously thought: remission is commonly achieved and recurrences are rare (Gunderson et al., 2011; Zanarini et al., 2012). Still, psychosocial and vocational impairment seem difficult to overcome; in BPD the impairment is often greater than the one observed in other personality disorders (Gunderson et al., 2011). The general aim of the current project is to study which psychopathological variables are most likely to explain the psychosocial functioning in BPD. Method: The sample consists of N=62 participants with borderline personality disorder (BPD) and N=60 treatment seeking participants (non-BPD control group). Each assessment comprises of self-report questionnaires and of a research interview. The primary measures consist of two semi-structured interviews administered at each assessment time: the Revised Diagnostic Interview for Borderlines (DIB-R; Zanarini et al., 1989) measuring BPD symptoms and the Revised Borderline Follow-up Interview (BFI-R; Zanarini et al., 1997) evaluating psychosocial functioning. Results: ANOVA tests will be performed to compare the baseline differences between groups in psychopathology as well as in psychosocial functioning. Additionally, regression analyses will be performed to determine which symptoms predict psychosocial functioning in our sample. Discussion: The present research has relevant clinical implications. Generally, psychotherapy in the context of BPD targets acute symptoms, which tend to resolve more quickly than temperamental ones; it is relevant to note that temperamental symptoms interfere greatly with psychosocial functioning (Zanarini, Frankeburg, Bradford Reich, & Fritzmaurice, 2016). The results of the current study could be useful in the context of thinking about ways to refine treatment in order to target temperamental symptoms and reduce psychosocial impairment.