Typical neuroleptics (i.e., haloperidol, chlorpromazine) are effective at ameliorating the positive psychotic symptoms of schizophrenia but are less efficacious in the treatment of negative symptoms, and there is limited evidence to support their ability to attenuate the cognitive dysfunction observed in schizophrenia (Meltzer et al. 1999). The primary mechanism through which typical neuroleptics achieve their effect is through dopamine (DA) blockade, but recent data suggest that DA blockade may be associated with diminished cognitive improvement despite effective clinical treatment. For example, in a recent molecular genetics study we have shown that subjects with greater DA availability display better cognitive performance on a task of executive functioning (Malhotra et al. in press). Thus, DA blockade may interfere with potential cognitive improvements associated with antipsychotic drug treatment.