Financial Disclosure: Drs Hyde, Zhang, and You are employees of Biogen Idec. Dr Rudick has received grant support for work related to this article from the National Institutes of Health, the National Multiple Sclerosis Society, the Nancy David Foundation, and Biogen Idec; and he has received compensation for consulting or speaking from Biogen Idec, Genzyme-Bayer, Novartis, Teva, Wyeth Pharmaceuticals, and Bayhill Therapeutics. Dr Cutter has served on the data and safety monitoring committees of Antisense Therapeutics Limited, Sanofi-Aventis, Bayhill Pharmaceuticals, BioMS Pharmaceuticals, Daichi-Sankyo, GlaxoSmithKline, Genmab Biopharmaceuticals, Eli Lilly, Medivation, PTC Therapeutics, Teva, Vivus, National Heart, Lung and Blood Institute, National Institute of Neurological Disorders and Stroke, and National MS Society; and he has received speaking fees, consulted, received grants, and/or served on the advisory boards of Alexion, Accentia, Bayhill, Bayer, Barofold, Biogen Idec, Diagenix, Novartis, Consortium of MS Centers, Kelin-Buendel, UCB Pharmaceuticals, Enzo Pharmaceuticals, Somnus Pharmaceuticals, Teva, University of Texas–Southwestern, and Ono Pharmaceuticals. Dr Bourdette has received honoraria and speaking fees from Biogen Idec, Pfizer, Serono, and Teva; and he has received unrestricted grants for professional and public education programs from Berlex Laboratories, Biogen Idec, Pfizer, Serono, and Teva. Dr Weinstock-Guttman has received consulting/speaking fees from and/or participated on advisory boards for Biogen Idec, Novartis, Sanofi-Aventis, Serono-Pfizer, and Teva. Dr Hyde holds stock in Biogen Idec.