Anxiety and depressive disorders often occur as comorbid illnesses and share many common symptoms. Risk factors for these disorders most likely include interactions of environmental and genetic factors. The presence of comorbid anxiety and depression adversely affects clinical and treatment outcomes. Selective serotonin reuptake inhibitors are usually considered first-line treatment for patients with these disorders, although alternative antidepressants or additional therapies are often necessary. Studies suggest that benzodiazepines, anticonvulsants, and atypical antipsychotics may be effective as augmentation therapy to optimize outcome, with buspirone and beta-blockers useful in some patients as well. Cognitive-behavioral therapy is also an effective therapeutic alternative for affected patients.