Background: iConquerMS is a multiple sclerosis (MS) participant-powered research network (PPRN), dedicated to engaging people affected by MS and researchers. iConquerMS participants complete baseline and biannual surveys that capture sociodemographic and clinical attributes, including symptom severity, quality of life, and other patient-reported outcomes. This MS PPRN is funded by the Patient-Centered Outcomes Research Institute, managed by Accelerated Cure Project for MS in partnership with Arizona State University and Feinstein Kean Healthcare, and governed by a Governing Board, Research Committee and Engagement Committee, most of whose members are people diagnosed with MS. To date, iConquerMS has developed and/or approved proposals for over 20 research projects in collaboration with external researchers from academia and industry. These projects are largely comprised of efforts to answer research questions using the existing detailed information or efforts that collect new data within the iConquerMS platform. Objectives: To characterize iConquerMS participants. Methods: In September 2020 there were 6,665 registrants of whom 2,743 completed sociodemographic and MS history surveys, reported their age (?18 years) and sex, and confirmed they had a diagnosis of MS, clinically isolated syndrome (CIS), or radiologically isolated syndrome (RIS). Descriptive statistics (medians, interquartile ranges [IQR], and percentages) were generated for the population. Results: The majority of the 2,743 study participants were female (78%), non-Hispanic (96%), white (91%), and USA residents (88%). Most participants had relapsing remitting MS (62%), followed by secondary progressive MS (20%), primary progressive MS (12%), and CIS/RIS (4%). Many were married/partnered (71%) but 20% lived alone. Amongst those with MS, their median age and disease duration were 52 years (IQR: 17.3) and 9.2 years (IQR: 13.6), respectively. A third of MS participants were early in their disease course (disease duration ?5 years) and a third had had MS for >15 years. In 1,348 participants who completed the Patient Determined Disease Steps (PDDS), a third had mild disability (PDDS?1), half had moderate disability (PDDS?2 and ?5), and the remaining participants had severe disability (PDDS>5). Conclusions: The iConquerMS network has grown into a powerful data resource and platform capable of facilitating research that answers questions that matter to those affected by MS.