This is a randomized, double-blind, placebo controlled, parallel-group, 3 site, 8-week trial of risperidone monotherapy in outpatient subjects with a lifetime bipolar I, II, or not otherwise specified (NOS) disorder, a lifetime panic or generalized anxiety disorder, and current, at least moderately, severe anxiety symptoms. Approximately 90 subjects will be enrolled to obtain 60 subjects who complete the 8-week trial. Subjects will be randomized to risperidone or placebo in a 1:1 ratio. No concomitant psychotropic medication will be allowed except for as needed (prn) lorazepam during the first two weeks for the management of affective and anxiety symptoms, and prn zolpidem and zaleplon throughout the study for the management of insomnia. 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.