The high prevalence of comorbid bipolar and borderline personality disorders and some diagnostic criteria similar to both conditions present both diagnostic and therapeutic challenges. This article delineates certain symptoms which, by careful history taking, may be attributed more closely to one of these two disorders. Making the correct primary diagnosis along with comorbid psychiatric conditions and choosing the appropriate type of psychotherapy and pharmacotherapy are critical steps to a patient's recovery. In this article, we will use a case example to illustrate some of the challenges the psychiatrist may face in diagnosing and treating borderline personality disorder. In addition, we will explore treatment strategies, including various types of therapy modalities and medication classes, which may prove effective in stabilizing or reducing a broad range of symptomotology associated with borderline personality disorder.