Over the past two and half decades, an increasing number therapies have become available to treat relapsing forms of multiple sclerosis. Despite their success in relapsing MS, many patients transition into progressive MS. The defining characteristic of progressive MS is the gradual, insidious decline in one or more neurologic functions. Both clinical trials and clinical practice have found that our ability to slow that insidious decline is limited. Similarly, our ability to reverse impairment and restore function is also limited. It is time to look back on what we have learned from relapsing MS and adapt those learnings to progressive MS. How do differences in pathology, imaging, fluid biomarkers, and response to therapies alter how we view progressive MS? How do clinical trials need to change to identify potentially promising treatments? How does clinical practice need to change to better capture the evolution of disease in progressive MS. Answers to these questions may help transform the challenges of progressive MS into the success weve seen with relapsing MS.