Deficits in new learning and memory in MS are a major complaint of patients, and have been noted to be a significant contributor to disability by numerous researchers. Modafinil is a psychostimulant medication, FDA approved for the treatment of Narcolepsy, with potential application for the treatment of learning and memory dysfunction in MS. This randomized clinical trial tests the efficacy of Modafinil for the treatment of new learning and memory deficits in MS.