Inclusion Criteria:  Be diagnosed with multiple sclerosis. Be determined by the study staff to have moderate to severe difficulty walking but still be able to walk while using the robotic exoskeleton. Have some difficulty thinking and problem solving as determined by my performance on a special test that I will take during the screening visit. Be between the ages of 18 and 75. Be free from flair ups of my MS Symptoms for at least one month prior to testing. Discuss with study staff how to maintain a constant level of my spasticity medication (for example baclofen) throughout the study. Be able to walk (with the use of one or more assistive device if needed). Have English as my primary language. Be able to physically fit into the exoskeleton device: height between 60 and 76", weight under 220 lbs. Be able to tolerate upright standing for 30 minutes with assistance if needed. Have normal joint range of motion for walking as determined by study staff. Have sufficient strength to use the hemiwalker, bilateral canes or walker while wearing the RE. Have stable blood pressure. Be willing and able to give informed consent. Be able and willing to comply with study procedures and follow directions and commands, verbal instructions, and follow-up requirements.  Exclusion Criteria:  Have a history of head injury, stroke, seizures, or any other significant neurological history other than MS. Have a high degree of difficulty in thinking and problem solving that prevents me from participating in the study as determined by my performance on a special test taken during the screening visit. Be currently taking steroids, benzodiazepines, antipsychotics, and/or neuroleptics as determined by study staff review of my medications. Be pregnant. Be completely reliant on a wheelchair. Have joint contracture or spasticity of any limb that limits normal range of motion during walking with assistive devices as determined by study staff. Have skin issues that would prevent wearing the RE. Have pressure sore stage 2 or higher located in an area that would negatively affect weight bearing, harness fit, or therapist assistance. Have orthopedic issues or history that will interfere with walking or limit the range of motion of the lower limbs (e.g., knee replacement, inflammation) Have been hospitalized for heart attack, heart surgery or acute heart failure within 3 months of enrollment in study. Have any other medical conditions that my doctor or physical therapist feels would affect my ability to use the robotic device. Have a pacemaker or other implanted electrical device, brain stimulator, aneurysm clip (metal clips on the wall of a large artery), metallic prostheses (including metal pins and rods, heart valves, and internal hearing aids [cochlear implants]), permanent eyeliner, implanted delivery pumps, or shrapnel fragments. Have dental implants- I should discuss any dental implants with the investigators. Have been told by my doctor that it is unsafe for me to have a regular MRI as part of my medical care.