The goals of this study are to determine: the safety of olanzapine and any side effects that might be associated with it, how olanzapine compares to placebo, whether olanzapine can help patients with symptoms of Borderline Personality Disorder (BPD), and how much olanzapine should be given to patients.

Inclusion Criteria:

• Patients must be of outpatient status at visit 1 and through visit 2.
• Patients must be 15 to 65 years of age at visit 1.
• Patients must meet all of the DSM-IV-TR General Diagnostic Criteria for a Personality Disorder and patients must meet DSM-IV-TR diagnostic criteria for BPD.
• The symptom severity as assessed by the total score of the ZAN-BPD, confirmed by a psychiatrist with training in the evaluation and assessment of BPD, must be greater than or equal to 9 at visit 2.
• Female patients of childbearing potential must test negative for pregnancy and must be using a medically accepted means of contraception throughout the course of the study.

Exclusion Criteria:

• Patients must not be investigators, study site personnel directly affiliated with the study, or immediate family of investigator site personnel directly affiliated with the study. Immediate family is defined as a spouse, parent, child, or sibling, whether biological or legally adopted.
• Persons employed by Lilly (that is, employees, temporary contract workers, or designees responsible for the conduct of the study). Immediate family of Lilly employees may participate in Lilly-sponsored clinical trials, but are not permitted to participate at a Lilly facility. Immediate family is defined as a spouse, parent, child, or sibling, whether biological or legally adopted.
• Patients must not have previously participated (have been randomized) or withdrawn from this study or any other Lilly sponsored study investigating olanzapine.
• Patients must not have had previous treatment with olanzapine unless, in the opinion of the investigator, the patients' previous treatment was inadequate in dose or duration to provide an accurate assessment of the therapy, or the effect of olanzapine was confounded by concomitant medication.
• Female patients must not be pregnant or nursing.