Clinical theorists have suggested that disturbed attachments are central to borderline personality disorder (BPD) psychopathology. This article reviews 13 empirical studies that examine the types of attachment found in individuals with this disorder or with dimensional characteristics of BPD. Comparison among the 13 studies is handicapped by the variety of measures and attachment types that these studies have employed. Nevertheless, every study concludes that there is a strong association between BPD and insecure attachment. The types of attachment found to be most characteristic of BPD subjects are unresolved, preoccupied, and fearful. In each of these attachment types, individuals demonstrate a longing for intimacy and--at the same time--concern about dependency and rejection. The high prevalence and severity of insecure attachments found in these adult samples support the central role of disturbed interpersonal relationships in clinical theories of BPD. This review concludes that these types of insecure attachment may represent phenotypic markers of vulnerability to BPD, suggesting several directions for future research.