Background: Schools are key social contexts for shaping development and behavior in youths; yet, little is known of their influence on adolescent personality disturbance. Method: A community-based sample of 592 adolescents was assessed for family and school experiences, Axis I psychiatric disorders, and Axis II personality disorder (PD) symptoms, and followed into young adulthood. Multiple regression analysis was used to estimate associations between adolescent-reported school climate and young adult PD symptoms independent of age, sex, family socioeconomic status; childhood maltreatment; Axis I disorder, PD symptoms, academic grades, and parental punishment in adolescence; and four dimensions of school climate. Results: Schools characterized as high in learning focus were related to cluster B (antisocial, borderline, histrionic, and narcissistic PD) symptom declines, whereas schools characterized as high in opportunities for student autonomy were related to cluster A (paranoid, schizoid, and schizotypal PD) symptom declines. In contrast, schools characterized as conflictual or supporting interpersonal informality/familiarity among students and teachers were related to increases in cluster A symptoms and cluster C (avoidant, dependent, and obsessive-compulsive PD) symptoms. Conclusions: Schools may exert both positive and negative influences on continuity of adolescent personality disturbance. The role of the school in guiding young people toward more favorable developmental pathways and alleviating personality disturbance is discussed.