High comorbidity, suicidal ideation, difficult temperament, and character are key symptoms of persons with borderline personality disorder (BPD). We investigated 478 persons, 40 of whom had a BPD according SCID-II, self-rating. Participants were examined with a semistructured interview and several self-rating questionnaires in their households. Taking the high comorbidity of persons with BPD into account, we compared the BPD group with four control groups with different axis 1 or personality disorders and one nonclinical group. Persons with BPD showed high comorbidity with affective, anxiety, and alcohol use disorders. With respect to suicidality, 75% reported that they wish to be dead at least sometimes, and about one-third said that they had already attempted suicide. Regarding temperament and character dimensions, our analyses revealed higher novelty seeking for persons with BPD compared to participants without BPD, although this difference was primarily attributable to males with BPD. Additionally, participants with BPD reported higher harm avoidance compared to control groups, while this was more distinctive for females. Finally, we found that persons with BPD had very low levels of self-directedness. This effect was independent from gender and was found in all group comparisons. Therapy of BPD should take into account high comorbidity and suicidality of patients. Moreover, our results show that low self-directedness seems to be specific for persons with BPD. Therefore, therapy must address those deficits by focusing on skills training as well as on aspects of maturation.