Borderline personality disorder (BPD) is among the most severe and perplexing mental disorders. Adults with BPD appear particularly exposed to severe difficulties in the transition to parenthood, infant caregiving, and the establishment of healthy early interactions. Studies on the offspring of parents with BPD show a high prevalence of social and emotional symptoms, including BPD features. This article reviews the possible consequences of this mental disorder for women during the transition to parenthood, for the quality of early mother–infant relationships, and for infant development. A presentation of a clinical case illustrates these issues, and some features of the preventive/therapeutic approach of these dyads are discussed.