We hope to learn whether ropinirole CR (controlled release formulation) is safe and effective when taken with an antidepressant to reduce the symptoms of depression. Adults who have a diagnosis of major depression and are currently taking an adequate dose of antidepressant medication will be sought for participation. They will continue to take the antidepressant medication and will receive ropinirole CR, an investigational medication, for eight weeks during which information will be collected about mood and cognitive functioning.