This is a randomized, double-blind, placebo controlled, parallel-group, 8-week trial of quetiapine SR monotherapy compared to divalproex sodium ER monotherapy in outpatient subjects with a lifetime bipolar I, II, or NOS disorder, a lifetime panic or generalized anxiety disorder, and current diagnosis at least moderately severe anxiety symptoms. Approximately 180 subjects will be randomized to obtain 90 subjects who complete the 8-week trial (30 completers per treatment group). This calculation is based on drop out rates in a similar patient population carried out by this group of collaborators. Subjects will be randomized to quetiapine SR or divalproex sodium ER or placebo in a 1:1:1 ratio. No concomitant psychotropic medication will be allowed throughout the study except for prn lorazepam during the first two weeks for the management of affective and anxiety symptoms, prn zolpidem and zaleplon for the management of insomnia and benztropine for the management of EPS. Throughout the study, psychiatric scales will be used to assess psychiatric symptoms and the presence of treatment-emergent adverse events will be monitored and recorded.