Borderline personality disorder (BPD) is a severe and chronic mental health condition involving marked emotional dysregulation that may impair parenting, parent-child relationships, and child development through pervasive and chaotic instabilities that accompany a parent’s intense fear of abandonment and resulting in hostile, low-cohesion family environments. BPD is prevalent in approximately 1.8% of the global population and stems from a complex interplay of genetic, neurobiological, and environmental factors, particularly involving childhood trauma. An estimated 23% to 59% of BPD adults are parents. The accompanying instability and impulsivity that exacerbates parenting-related stress in BPD may negatively impact children across a host of domains. The traits and behaviors associated with BPD may distort parent-child dynamics and often lead to the reversal of roles, wherein children assume the parent’s caregiving responsibilities. The impact of a parent’s BPD upon children has been observed even in the early ages of development via dazed gazes and inconsistent responsiveness in infants. The children of a BPD parent incur a higher risk of numerous disabling mental health, emotional, and behavioral impairments and of exhibiting BPD traits by adolescence. The economic burden of BPD extends beyond high direct medical costs and involves poor patterns of employment to further strain families, while stigma and isolation compound existing humanistic disabilities. Evidence-based psychotherapies, including dialectical behavior therapy and mentalization-based treatment, may improve emotional stability and parenting consistency, while social support may mitigate stress. There is no established cure for BPD, though the condition can go into remission. Early interventions targeting attachment and reflective capacity are vital to interrupt BPD’s intergenerational transmission, reducing profound psychosocial burdens in families. The purpose of this entry is to review BPD’s severe impact on parenting, families, and children, emphasizing the need for targeted interventions to address its disabling consequences.