The intent of this study is to demonstrate the efficacy and safety of Immune Globulin Intravenous (Human), 10% Caprylate/Chromatography Purified (IGIV-C) in newly or previously diagnosed CIDP subjects. Eight courses of treatment with either placebo or IGIV-C will occur every 3 weeks. Neurological function will be measured by Inflammatory Neuropathy Cause and Treatment (INCAT) scores. Patients who deteriorate or show no improvement between day 16 and month 6 will receive the alternate study drug for an additional 6 months.