This study compared aspects of the functioning of mothers with borderline personality disorder (BPD) to those of mothers without psychiatric disorder using two different conceptualizations of attachment theory. The Adult Attachment Interviews (AAIs) of 32 mothers were classified using both the Main and Goldwyn method (M&G) and the Dynamic-Maturational Model method (DMM). We found that mothers with BPD recalled more danger, reported more negative effects of danger, and gave evidence of more unresolved psychological trauma tied to danger than other mothers. We also found that the DMM classifications discriminated between the two groups of mothers better than the M&G classifications. Using the DMM method, the AAIs of BPD mothers were more complex, extreme, and had more indicators of rapid shifts in arousal than those of other mothers. Representations drawn from the AAI, using either classificatory method, did not match the representations of the mother's child drawn from the Working Model of the Child Interview; mothers with very anxious DMM classifications were paired with secure-balanced child representations. We propose that the DMM offers greater clinical utility, conceptual coherence, empirical validity, and coder reliability than the M&G.