Of 50 patients with borderline personality disorder, 100% reported disturbed but nonpsychotic thought, 40% (N = 20) reported quasi-psychotic thought, and none reported true psychotic thought during the past 2 years; only 14% (N = 7) reported ever experiencing true psychotic thought. Disturbed and quasi-psychotic thought was significantly more common among these patients than among patients with other axis II disorders or schizophrenia and normal control subjects; however, true psychotic thought was significantly more common among schizophrenic patients. While disturbed thought was also common among axis II disorder and schizophrenic patients, quasi-psychotic thought was reported by only one of these subjects, suggesting that quasi-psychotic thought may be a marker for borderline personality disorder.