The goals of this study are to study MMFS-202-302 in a double blind, randomized, placebo-controlled 9-week study of its effect on ameliorating cognitive deficits in 60 patients with schizophrenia or schizoaffective disorder with stable levels of positive symptoms. Secondary end points will include changes in positive and negative symptoms. One dose of MMFS-202-302 will be studied and compared with placebo as adjunctive treatment to atypical antipsychotic drug treatment.