A Study Of PF-03463275 As Add-On Therapy In Outpatients With Persistent Negative Symptoms Of Schizophrenia

Inclusion Criteria: * Subjects must have a current diagnosis of schizophrenia of paranoid (295.30), disorganized (295.10), or undifferentiated (295.90) subtype in the residual phase. * Subjects must be in ongoing maintenance antipsychotic monotherapy with risperidone, olanzapine, quetiapine, ziprasidone, paliperidone, or aripiprazole. Subjects must be on a stable medication treatment regimen for at least 2 months. * Evidence of stable symptomatology at least 3 months. Exclusion Criteria: * Female subjects who are pregnant or breastfeeding. * Subjects with evidence or history of a clinically significant medical condition which would increase risk or which could interfere with the interpretation of trial results. * Subjects who have DSM IV defined psychoactive substance dependence (including alcohol and excluding nicotine and caffeine dependence) within 12 months of screening or substance abuse within 3 months prior to screening.