Numerous studies have reported associations between poor performance on neuropsychological measures of executive functions and antisocial behavior. These findings are supported by neuroimaging studies that report prefrontal cortical abnormalities in aggressive subjects. Epidemiological studies indicate that patients diagnosed with schizophrenia perform poorly on executive tasks and are at higher risk for violent behavior than those without mental illness.These data suggest that aggression in schizophrenia may be the result of prefrontal abnormalities, and consequent executive dysfunction. A widely used measure of executive functioning is the Stroop paradigm, which requires frontally-mediated cognitive processes such as response inhibition, interference resolution and behavioral conflict resolution. However, implementation of the task, in its traditional form, is problematic for fMRI research. Verbal responses can introduce movement artifacts and the use of covert responses limits evaluation of subjects’ performance. In this ongoing study the investigators are validating a modified version of the Stroop task for use in fMRI experiments with violent and non-violent schizophrenic patients and healthy controls. The modified task requires subjects to respond to directional stimuli by means of a 2-choice button press. Verbal and nonverbal stimuli are presented either alone (neutral condition) or together (congruent and incongruent conditions). Preliminary results from 9 patients indicated robust interference effects in terms of both accuracy and reaction time. Final results from patients and controls are presented and their implication for the use of this new test in future fMRI research is discussed. Schizophrenia Research, 60 (supl), 122.