Participants in this double blind study will be randomly assigned to one of three study groups. Participants assigned to the first study group will receive capsules containing 500 mg of an EPA-enriched omega-3 fatty acid preparation. Participants assigned to the second study group will receive capsules containing 500 mg of pure DHA. Participants assigned to the third study group will receive capsules containing a placebo. The study will last approximately 9 weeks. This will include an initial screening the first week followed by an 8-week period during which all participants will take two capsules of their assigned treatment each morning. Participants will attend a total of six study visits. The initial visit will last approximately 2 hours and will include a psychiatric assessment, urine and blood collection, an electrocardiogram (EKG), and a Food Processor Questionnaire. Participants who qualify for further participation will then enter a 1-week washout period during which they will stop taking any current psychotropic medication. At the second study visit, participants will be assigned to their treatment group. Upon starting assigned treatments, participants will then return for study visits every 2 weeks to report any possible side effects and to complete standard psychiatric assessment tests. All of these study visits will take approximately 1 hour, except the last, which will take 2 hours. In addition to the psychiatric assessment and review of side effects, the final study visit will also include a physical exam and blood collection.