See termination reason in detailed description.

This study is examining the efficacy of PF-03463275 compared to placebo in treating negative symptoms of schizophrenia when added to ongoing antipsychotic treatment in stable outpatients with schizophrenia.

The study was terminated on August 25, 2010 because the study's scientific validity could no longer be supported. The decision to terminate the trial was not based on any safety concerns.

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.