Borderline personality disorder (BPD) is a severe and chronic mental illness. Self-reported borderline features correlate highly with a diagnosis (affective instability, negative relationships, unstable sense of self, self-harm). Etiological factors of BPD include childhood maltreatment. The current study compared the experience of maltreatment in adolescent offspring of mothers with BPD, who are themselves at risk of developing the disorder, with that of offspring of mothers with no current diagnosis. Participants were 56 adolescents aged 14 to 18 years. In all, 93% of the adolescents whose mothers had BPD experienced maltreatment compared with 60% of comparisons. Specifically, adolescent offspring of mothers with BPD experienced more physical abuse, emotional abuse, and neglect, but not more sexual abuse, than did comparisons. Dimensions of maltreatment (severity, multiple subtypes, chronicity) were associated with adolescents' own total borderline features. We discuss implications for the intergenerational transmission of BPD and for clinical interventions. (PsycINFO Database Record