The literature suggests that when a patient is prescribed more than one antipsychotic for at least 30 days, he or she is likely to continue on that combination. In this 12 week study 100 adult patients being treated on more than one antipsychotic medication for at least 30 days will be recruited. In order to control for the natural course of the illness, patients will be randomly assigned to one of two groups: the first group will continue the second medication hidden in a capsule at the same dose, while the second group will be given an inactive capsule (placebo) - the capsules in both group will be identical such that neither the patient nor the treating doctor will be able to identify the group assignment.