Cognitive deficits are a core feature of schizophrenia. As a target of intervention, improvements in cognition may lead to improvements in functional outcome. The present paper is the first report, to our knowledge, on the neurocognitive effects of aripiprazole. Unlike other second-generation antipsychotics, aripiprazole is a D(2) and D(3) receptor partial agonist. It is unknown what effects this unusual pharmacological profile may yield on neurocognition. The present open-label study included data on 169 patients with schizophrenia or schizoaffective disorder who were randomly treated with aripiprazole or olanzapine. Subjects received a neurocognitive battery at baseline, week 8, and 26. The aripiprazole group had a significantly greater dropout rate than the olanzapine group. Neurocognitive data were reduced through a principal components analysis that yielded a three-factor solution. The factors were general cognitive functioning, executive functioning, and verbal learning. For general cognitive functioning, both groups improved from baseline and the effects were relatively stable over the 26-week protocol. There were no differential treatment effects. For executive functioning, neither group improved significantly from baseline. For verbal learning, the aripiprazole group improved significantly from baseline to the 8th and 26th week of assessment, and there was a between-group effect favoring aripiprazole over olanzapine that was largely attributable to the differences in performance within the 8th week. Separate analyses were conducted for a measure of sustained attention (Continuous Performance Test-Identical Pairs). There were no differential treatment effects on this measure. The findings from this open-label study suggest that the neurocognitive effects of aripiprazole are at least as good as those of olanzapine.