Linehan (1993) theorized that the experience of invalidating parenting interacts with emotional vulnerability in the development of borderline personality disorder (BPD). Parental psychological control is a type of invalidating parenting, defined as manipulation by parents of their offspring’s psychological and emotional expression and experience (Barber, 1996). In a normative sample of adolescent females, adolescent-reported maternal psychological control was related to maternal borderline symptoms (Zalewski et al., 2014). The current study expanded on these findings to sample mothers with a diagnosis of BPD (n = 28) and normative comparisons (n = 28) with male and female adolescents aged 14–18. We assessed maternal and adolescent self-reported borderline features (affective instability, negative relationships, identity disturbance, and self-harm) and coded maternal psychological control from filmed problem-solving interactions. Controlling for current major depressive disorder and family income, mothers with BPD used more total psychological control with their adolescents in comparison with normative mothers. Further, maternal psychological control was positively associated with all mothers’ borderline features and with adolescent affective instability. Finally, we found a significant indirect effect for maternal affective instability between maternal total psychological control and adolescent affective instability. We discuss adolescents’ risk of developing BPD themselves and prevention and treatment implications.