We propose to investigate the efficacy of amantadine as a weight-stabilizing agent in a population of first-episode psychotic subjects just beginning treatment with antipsychotic agents. This population is generally young and medically healthy, without contraindications to amantadine. They are often of normal body mass index and without obesity-related medical problems. They have much to gain in preventing the weight gain which so often progresses steadily over the course of treatment, is difficult to reverse and results in significant morbidity and mortality. Additionally, the first episode psychotic population tends to take fewer concomitant psychiatric medications. This is important since these medications may cause weight gain (long term use of mirtazapine, lithium, depakote) or weight loss (short term use of SSRI's) which could confound the effectiveness of amantadine to combat weight gain.