Bipolar disorder, while commonly encountered in the primary care setting, is often misdiagnosed or undiagnosed. In the DSM-IV-TR, patients could be diagnosed as being in a mixed state only if they had concurrent manic and depressive symptoms; while this occurs in some patients, many more experience subsyndromal mixed symptoms that would disqualify a "mixed state" diagnosis. The recently released DSM-5 attempts to capture this large proportion of patients with subsyndromal mixed symptoms with the inclusion of the "mixed specifier." The presence of such subsyndromal mixed symptoms has significant implications for both diagnosis and treatment. For those presenting with major depressive disorder with subsyndromal manic symptoms, clinicians must be vigilant for the development of full-blown bipolar disease. In treating this group, selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors remain first-line therapy, but augmentation with other therapies is often required. If a diagnosis of bipolar disorder is confirmed and the patient is experiencing a depressive phase, traditional antidepressants should be avoided. For those presenting with mania and mixed depressive symptoms, treatment with a combination of atypical antipsychotics and mood stabilizers is best.