The Guy's Neurological Disability Scale (GNDS) was originally developed in the United Kingdom to measure disability in multiple sclerosis (MS). The purpose of this study was to test the reliability, validity, and sensitivity of the Americanized version of the GNDS. The following five research questions were considered: (1) Is there convergent validity of the Americanized version of the GNDS as evidenced by a significant relationship with the Short Form 36® (SF-36) and Activities of Daily Living Self-Care for MS Scale? (2) Does the Americanized version of the GNDS have the same four-factor structure as reported in the psychometric testing of the original GNDS? (3) Is the Americanized version of the GNDS a reliable measure when examined with a 2-week retest? (4) Does the Americanized version of the GNDS have internal consistency? (5) Is the Americanized version of the GNDS sensitive to changes in neurological disability from MS over time? Participants were diagnosed with relapsing-remitting MS and a history of one or more relapses in the previous 2 years. The sample included 253 participants—87% were women (n = 219), 13% were men (n = 32), and two participants did not indicate their sex. They ranged in age from 22 to 77 years (M = 46, SD = 9). The Americanized version of the GNDS was found to be a reliable, valid, and sensitive multidimensional measure of neurological disability for individuals with MS.