The proposed study would evaluate the benefits of riluzole add-on treatment to patients with schizophrenia who are already receiving medications, but still experience symptoms. Neuroprotective medication riluzole is currently approved for treatment of amyotrophic lateral sclerosis (Lou Gehrig's disease), a severe neurological illness. Due to its unique mechanism of action, riluzole, if effective in helping the symptoms of schizophrenia, would open novel directions in treatment of schizophrenia.