There is a dearth of prospective information regarding adolescent precursors of borderline personality disorder (BPD). This study aimed to determine the unique associations between early maladaptive family functioning, parental psychiatric diagnoses, proband early onset psychiatric diagnosis, and BPD symptoms in adulthood using an existing longitudinal study. Participants were randomly selected from 9 high schools in western Oregon. A total of 1,709 students (ages 14–18 years) completed 2 assessments during adolescence. All adolescents with a history of a depressive disorder (n = 360) or a history of nonmood disorders (n = 284) and a random sample of adolescents with no history of psychopathology (n = 457) were invited to participate in a 3rd and 4th evaluation when participants were on average 24 years old and 30 years old, respectively. Biological parents were interviewed at the 3rd assessment. The multivariate model with all early risk factors found that maternal–child discord (p < .05), maternal BPD (p < .05), paternal substance use disorder (SUD; p < .05), and proband depression (p < .05), SUD (p < .001), and suicidality (p < .05) were associated with later BPD symptoms. Maternal SUD and proband anxiety, conduct disorder/oppositional defiant disorder, and attention-deficit/hyperactivity disorder were also associated with proband BPD symptoms in univariate analyses, but were no longer significant when the other risk factors were included in the model. Multivariate assessment models are needed to identify unique risk factors for BPD. This will enhance the efficiency of screening efforts for early detection of risk.