Abstract: Relatively absent from previous studies of the pharmacotherapy for bipolar disorder is examination of the impact of comorbidity on treatment choices. This has occurred despite the presence of high levels of comorbid anxiety and substance use disorders, and the association of these disorders with severity and course markers of bipolar disorder. In this study, we examined comorbid disorders, identified by structured interviews, and the pharmacotherapy reported at study entry by the first 1000 patients entered into a large, multicenter study of bipolar disorder (Systematic Treatment Enhancement Program for Bipolar Disorder). Our study focused on the degree to which comorbid conditions are linked to the reported use of mood stabilizers deemed "minimally adequate" and the association between specific comorbidities and pharmacotherapy treatment, such as the use of anxiolytics in patients with anxiety disorders. Despite the presence of high levels of comorbidity, the presence of these disorders was only minimally associated with pharmacotherapy. Of the sample of bipolar outpatients, only 59% reported pharmacotherapy use meeting criteria for "minimally adequate" mood stabilizer, regardless of comorbid diagnoses, rapid cycling, or bipolar I or II status. Moreover, the cross-sectional use of "comorbidity-specific" pharmacotherapy for anxiety disorders, substance use disorders, and attention deficit disorder in this outpatient sample of patients with bipolar disorders was limited, suggesting that comorbid conditions in patients with bipolar disorder may be undertreated. Our findings highlight the need for greater clinical guidance and treatment options for patients with bipolar disorder and comorbidity.