Why are women diagnosed borderline more than men?

DSM-IV-TR states that borderline personality disorder (BPD) is "diagnosed predominantly (about 75%) in females." A 3:1 female to male gender ratio is quite pronounced for a mental disorder and, consequently, has led to speculation about its cause and to some empirical research. The essential question is whether the higher rate of BPD observed in women is a result of a sampling or diagnostic bias, or is it a reflection of biological or sociocultural differences between women and men? Data to address these issues are reviewed. The differential gender prevalence of BPD in clinical settings appears to be largely a function of sampling bias. True prevalence by gender is unknown. The modest empirical support for diagnostic biases of various kinds would not account for a wide difference in prevalence between the genders. Biological and sociocultural factors provide potentially illuminating hypotheses, should the true prevalence of BPD differ by gender.