Generalized social anxiety disorder (GSAD) is one of the most common psychiatric disorders, and often causes significant distress and dysfunction in affected individuals. Although currently available treatments for GSAD are effective, most individuals have residual symptoms after initial psychosocial or psychopharmacologic intervention. Further treatment is necessary for such individuals, but sufficient research has not been done to guide clinicians on what the safest and most effective next step may be. This study will compare the effectiveness of either combining clonazepam or placebo with sertraline or completely switching to venlafaxine in treating GSAD in individuals who have not responded to treatment with sertraline. This study will also examine predictors of treatment response, including factors such as age at disease onset, duration of illness, comorbidities, and genes that influence serotonin and catecholamine metabolism.