The purpose of this study was to identify factors associated with increased likelihood of reporting fear of falling (FoF) among people with multiple sclerosis (MS) and factors associated with activity curtailment among the subset of individuals reporting FoF. Cross-sectional data from telephone interviews with 1064 individuals with MS, aged 45-90 years living in the Midwestern United States were used. Logistic regression models examined factors associated with FoF and with activity curtailment among individuals reporting FoF. Of the participants, 63.5% reported FoF. Increased likelihood of reporting FoF was associated with being female, experiencing greater MS symptom interference during everyday activities, history of a fall in the past 6 months, and using a walking aid. Among participants reporting FoF, 82.6% reported curtailing activity. Increased likelihood of activity curtailment among people reporting FoF was associated with using a walking aid, needing moderate or maximum assistance with instrumental activities of daily living, and having less than excellent self-reported mental health. We concluded that FoF and associated activity curtailment are common among people aged 45-90 with MS. While FoF and associated activity curtailment may be appropriate responses to fall risk, the findings suggest that factors beyond realistic appraisal of fall risk may be operating.