This study is a randomized, double blind, sham controlled study to evaluate the efficacy of repetitive transcranial magnetic stimulation as a treatment for working memory deficits in individuals with schizophrenia or schizoaffective disorder between 18 and 59 years of age. The study duration is approximately 3 months, with the rTMS sessions lasting for 4 weeks, 5 times a week, for about 1 hour each. Several scales will be used to assess symptom severity as part of the clinical assessment. Cognition will be assessed using a validated battery and the N-back task.